diff --git a/Cargo.lock b/Cargo.lock
index 1002d1c894e16..c1f9ef0886c5e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1567,7 +1567,7 @@ dependencies = [
 
 [[package]]
 name = "frame-metadata"
-version = "11.0.0-rc6"
+version = "12.0.0-rc6"
 dependencies = [
  "parity-scale-codec",
  "serde",
@@ -1636,6 +1636,7 @@ dependencies = [
 name = "frame-support-test"
 version = "2.0.0-rc6"
 dependencies = [
+ "frame-metadata",
  "frame-support",
  "parity-scale-codec",
  "pretty_assertions",
diff --git a/frame/metadata/Cargo.toml b/frame/metadata/Cargo.toml
index 2a00ecd85d120..2980eb1cf496d 100644
--- a/frame/metadata/Cargo.toml
+++ b/frame/metadata/Cargo.toml
@@ -1,6 +1,6 @@
 [package]
 name = "frame-metadata"
-version = "11.0.0-rc6"
+version = "12.0.0-rc6"
 authors = ["Parity Technologies <admin@parity.io>"]
 edition = "2018"
 license = "Apache-2.0"
diff --git a/frame/metadata/src/lib.rs b/frame/metadata/src/lib.rs
index c0eeb76b6f976..109f33f420191 100644
--- a/frame/metadata/src/lib.rs
+++ b/frame/metadata/src/lib.rs
@@ -362,8 +362,10 @@ pub enum RuntimeMetadata {
 	V9(RuntimeMetadataDeprecated),
 	/// Version 10 for runtime metadata. No longer used.
 	V10(RuntimeMetadataDeprecated),
-	/// Version 11 for runtime metadata.
-	V11(RuntimeMetadataV11),
+	/// Version 11 for runtime metadata. No longer used.
+	V11(RuntimeMetadataDeprecated),
+	/// Version 12 for runtime metadata.
+	V12(RuntimeMetadataV12),
 }
 
 /// Enum that should fail.
@@ -387,7 +389,7 @@ impl Decode for RuntimeMetadataDeprecated {
 /// The metadata of a runtime.
 #[derive(Eq, Encode, PartialEq, RuntimeDebug)]
 #[cfg_attr(feature = "std", derive(Decode, Serialize))]
-pub struct RuntimeMetadataV11 {
+pub struct RuntimeMetadataV12 {
 	/// Metadata of all the modules.
 	pub modules: DecodeDifferentArray<ModuleMetadata>,
 	/// Metadata of the extrinsic.
@@ -395,7 +397,7 @@ pub struct RuntimeMetadataV11 {
 }
 
 /// The latest version of the metadata.
-pub type RuntimeMetadataLastVersion = RuntimeMetadataV11;
+pub type RuntimeMetadataLastVersion = RuntimeMetadataV12;
 
 /// All metadata about an runtime module.
 #[derive(Clone, PartialEq, Eq, Encode, RuntimeDebug)]
@@ -407,6 +409,9 @@ pub struct ModuleMetadata {
 	pub event: ODFnA<EventMetadata>,
 	pub constants: DFnA<ModuleConstantMetadata>,
 	pub errors: DFnA<ErrorMetadata>,
+	/// Define the index of the module, this index will be used for the encoding of module event,
+	/// call and origin variants.
+	pub index: u8,
 }
 
 type ODFnA<T> = Option<DFnA<T>>;
@@ -420,6 +425,6 @@ impl Into<sp_core::OpaqueMetadata> for RuntimeMetadataPrefixed {
 
 impl Into<RuntimeMetadataPrefixed> for RuntimeMetadataLastVersion {
 	fn into(self) -> RuntimeMetadataPrefixed {
-		RuntimeMetadataPrefixed(META_RESERVED, RuntimeMetadata::V11(self))
+		RuntimeMetadataPrefixed(META_RESERVED, RuntimeMetadata::V12(self))
 	}
 }
diff --git a/frame/scheduler/src/lib.rs b/frame/scheduler/src/lib.rs
index 3024c7d6d0d05..c91131005972b 100644
--- a/frame/scheduler/src/lib.rs
+++ b/frame/scheduler/src/lib.rs
@@ -438,6 +438,25 @@ impl<T: Trait> Module<T> {
 		}
 	}
 
+	/// Helper to migrate scheduler when the pallet origin type has changed.
+	pub fn migrate_origin<OldOrigin: Into<T::PalletsOrigin> + codec::Decode>() {
+		Agenda::<T>::translate::<
+			Vec<Option<Scheduled<<T as Trait>::Call, T::BlockNumber, OldOrigin, T::AccountId>>>, _
+		>(|_, agenda| Some(
+			agenda
+				.into_iter()
+				.map(|schedule| schedule.map(|schedule| Scheduled {
+					maybe_id: schedule.maybe_id,
+					priority: schedule.priority,
+					call: schedule.call,
+					maybe_periodic: schedule.maybe_periodic,
+					origin: schedule.origin.into(),
+					_phantom: Default::default(),
+				}))
+				.collect::<Vec<_>>()
+		));
+	}
+
 	fn do_schedule(
 		when: DispatchTime<T::BlockNumber>,
 		maybe_periodic: Option<schedule::Period<T::BlockNumber>>,
@@ -632,6 +651,7 @@ mod tests {
 		traits::{BlakeTwo256, IdentityLookup},
 	};
 	use frame_system::{EnsureOneOf, EnsureRoot, EnsureSignedBy};
+	use substrate_test_utils::assert_eq_uvec;
 	use crate as scheduler;
 
 	mod logger {
@@ -1161,8 +1181,6 @@ mod tests {
 
 	#[test]
 	fn migration_to_v2_works() {
-		use substrate_test_utils::assert_eq_uvec;
-
 		new_test_ext().execute_with(|| {
 			for i in 0..3u64 {
 				let k = i.twox_64_concat();
@@ -1264,4 +1282,118 @@ mod tests {
 			assert_eq!(StorageVersion::get(), Releases::V2);
 		});
 	}
+
+	#[test]
+	fn test_migrate_origin() {
+		new_test_ext().execute_with(|| {
+			for i in 0..3u64 {
+				let k = i.twox_64_concat();
+				let old: Vec<Option<Scheduled<_, _, u32, u64>>> = vec![
+					Some(Scheduled {
+						maybe_id: None,
+						priority: i as u8 + 10,
+						call: Call::Logger(logger::Call::log(96, 100)),
+						origin: 3u32,
+						maybe_periodic: None,
+						_phantom: Default::default(),
+					}),
+					None,
+					Some(Scheduled {
+						maybe_id: Some(b"test".to_vec()),
+						priority: 123,
+						origin: 2u32,
+						call: Call::Logger(logger::Call::log(69, 1000)),
+						maybe_periodic: Some((456u64, 10)),
+						_phantom: Default::default(),
+					}),
+				];
+				frame_support::migration::put_storage_value(
+					b"Scheduler",
+					b"Agenda",
+					&k,
+					old,
+				);
+			}
+
+			impl Into<OriginCaller> for u32 {
+				fn into(self) -> OriginCaller {
+					match self {
+						3u32 => system::RawOrigin::Root.into(),
+						2u32 => system::RawOrigin::None.into(),
+						_ => unreachable!("test make no use of it"),
+					}
+				}
+			}
+
+			Scheduler::migrate_origin::<u32>();
+
+			assert_eq_uvec!(Agenda::<Test>::iter().collect::<Vec<_>>(), vec![
+				(
+					0,
+					vec![
+					Some(ScheduledV2::<_, _, OriginCaller, u64> {
+						maybe_id: None,
+						priority: 10,
+						call: Call::Logger(logger::Call::log(96, 100)),
+						maybe_periodic: None,
+						origin: system::RawOrigin::Root.into(),
+						_phantom: PhantomData::<u64>::default(),
+					}),
+					None,
+					Some(ScheduledV2 {
+						maybe_id: Some(b"test".to_vec()),
+						priority: 123,
+						call: Call::Logger(logger::Call::log(69, 1000)),
+						maybe_periodic: Some((456u64, 10)),
+						origin: system::RawOrigin::None.into(),
+						_phantom: PhantomData::<u64>::default(),
+					}),
+				]),
+				(
+					1,
+					vec![
+						Some(ScheduledV2 {
+							maybe_id: None,
+							priority: 11,
+							call: Call::Logger(logger::Call::log(96, 100)),
+							maybe_periodic: None,
+							origin: system::RawOrigin::Root.into(),
+							_phantom: PhantomData::<u64>::default(),
+						}),
+						None,
+						Some(ScheduledV2 {
+							maybe_id: Some(b"test".to_vec()),
+							priority: 123,
+							call: Call::Logger(logger::Call::log(69, 1000)),
+							maybe_periodic: Some((456u64, 10)),
+							origin: system::RawOrigin::None.into(),
+							_phantom: PhantomData::<u64>::default(),
+						}),
+					]
+				),
+				(
+					2,
+					vec![
+						Some(ScheduledV2 {
+							maybe_id: None,
+							priority: 12,
+							call: Call::Logger(logger::Call::log(96, 100)),
+							maybe_periodic: None,
+							origin: system::RawOrigin::Root.into(),
+							_phantom: PhantomData::<u64>::default(),
+						}),
+						None,
+						Some(ScheduledV2 {
+							maybe_id: Some(b"test".to_vec()),
+							priority: 123,
+							call: Call::Logger(logger::Call::log(69, 1000)),
+							maybe_periodic: Some((456u64, 10)),
+							origin: system::RawOrigin::None.into(),
+							_phantom: PhantomData::<u64>::default(),
+						}),
+					]
+				)
+			]);
+		});
+	}
 }
diff --git a/frame/support/Cargo.toml b/frame/support/Cargo.toml
index dc1286d84e968..8eb86980a50ea 100644
--- a/frame/support/Cargo.toml
+++ b/frame/support/Cargo.toml
@@ -16,7 +16,7 @@ targets = ["x86_64-unknown-linux-gnu"]
 log = "0.4"
 serde = { version = "1.0.101", optional = true, features = ["derive"] }
 codec = { package = "parity-scale-codec", version = "1.3.1", default-features = false, features = ["derive"] }
-frame-metadata = { version = "11.0.0-rc6", default-features = false, path = "../metadata" }
+frame-metadata = { version = "12.0.0-rc6", default-features = false, path = "../metadata" }
 sp-std = { version = "2.0.0-rc6", default-features = false, path = "../../primitives/std" }
 sp-io = { version = "2.0.0-rc6", default-features = false, path = "../../primitives/io" }
 sp-runtime = { version = "2.0.0-rc6", default-features = false, path = "../../primitives/runtime" }
diff --git a/frame/support/procedural/src/construct_runtime/mod.rs b/frame/support/procedural/src/construct_runtime/mod.rs
index 867b6a72f4586..c51582fdd05a1 100644
--- a/frame/support/procedural/src/construct_runtime/mod.rs
+++ b/frame/support/procedural/src/construct_runtime/mod.rs
@@ -19,15 +19,86 @@ mod parse;
 
 use frame_support_procedural_tools::syn_ext as ext;
 use frame_support_procedural_tools::{generate_crate_access, generate_hidden_includes};
-use parse::{ModuleDeclaration, RuntimeDefinition, WhereSection};
+use parse::{ModuleDeclaration, RuntimeDefinition, WhereSection, ModulePart};
 use proc_macro::TokenStream;
-use proc_macro2::TokenStream as TokenStream2;
+use proc_macro2::{TokenStream as TokenStream2};
 use quote::quote;
 use syn::{Ident, Result, TypePath};
+use std::collections::HashMap;
 
 /// The fixed name of the system module.
 const SYSTEM_MODULE_NAME: &str = "System";
 
+/// The complete definition of a module with the resulting fixed index.
+#[derive(Debug, Clone)]
+pub struct Module {
+	pub name: Ident,
+	pub index: u8,
+	pub module: Ident,
+	pub instance: Option<Ident>,
+	pub module_parts: Vec<ModulePart>,
+}
+
+impl Module {
+	/// Get resolved module parts
+	fn module_parts(&self) -> &[ModulePart] {
+		&self.module_parts
+	}
+
+	/// Find matching parts
+	fn find_part(&self, name: &str) -> Option<&ModulePart> {
+		self.module_parts.iter().find(|part| part.name() == name)
+	}
+
+	/// Return whether module contains part
+	fn exists_part(&self, name: &str) -> bool {
+		self.find_part(name).is_some()
+	}
+}
+
+/// Convert from the parsed module to their final information.
+/// Assign index to each modules using same rules as rust for fieldless enum.
+/// I.e. implicit are assigned number incrementedly from last explicit or 0.
+fn complete_modules(decl: impl Iterator<Item = ModuleDeclaration>) -> syn::Result<Vec<Module>> {
+	let mut indices = HashMap::new();
+	let mut last_index: Option<u8> = None;
+
+	decl
+		.map(|module| {
+			let final_index = match module.index {
+				Some(i) => i,
+				None => last_index.map_or(Some(0), |i| i.checked_add(1))
+					.ok_or_else(|| {
+						let msg = "Module index doesn't fit into u8, index is 256";
+						syn::Error::new(module.name.span(), msg)
+					})?,
+			};
+
+			last_index = Some(final_index);
+
+			if let Some(used_module) = indices.insert(final_index, module.name.clone()) {
+				let msg = format!(
+					"Module indices are conflicting: Both modules {} and {} are at index {}",
+					used_module,
+					module.name,
+					final_index,
+				);
+				let mut err = syn::Error::new(used_module.span(), &msg);
+				err.combine(syn::Error::new(module.name.span(), msg));
+				return Err(err);
+			}
+
+			Ok(Module {
+				name: module.name,
+				index: final_index,
+				module: module.module,
+				instance: module.instance,
+				module_parts: module.module_parts,
+			})
+		})
+		.collect()
+}
+
 pub fn construct_runtime(input: TokenStream) -> TokenStream {
 	let definition = syn::parse_macro_input!(input as RuntimeDefinition);
 	construct_runtime_parsed(definition)
@@ -52,19 +123,16 @@ fn construct_runtime_parsed(definition: RuntimeDefinition) -> Result<TokenStream
 		..
 	} = definition;
 
-	let modules = modules.into_pairs().map(|v| v.into_value()).collect::<Vec<_>>();
-
-	// Assert we have system module declared
-	let system_module = match find_system_module(modules.iter()) {
-		Some(sm) => sm,
-		None => {
-			return Err(syn::Error::new(
-				modules_token.span,
-				"`System` module declaration is missing. \
-				 Please add this line: `System: frame_system::{Module, Call, Storage, Config, Event<T>},`",
-			))
-		}
-	};
+	let modules = complete_modules(modules.into_iter())?;
+
+	let system_module = modules.iter()
+		.find(|decl| decl.name == SYSTEM_MODULE_NAME)
+		.ok_or_else(|| syn::Error::new(
+			modules_token.span,
+			"`System` module declaration is missing. \
+			 Please add this line: `System: frame_system::{Module, Call, Storage, Config, Event<T>},`",
+		))?;
+
 	let hidden_crate_name = "construct_runtime";
 	let scrate = generate_crate_access(&hidden_crate_name, "frame-support");
 	let scrate_decl = generate_hidden_includes(&hidden_crate_name, "frame-support");
@@ -79,7 +147,7 @@ fn construct_runtime_parsed(definition: RuntimeDefinition) -> Result<TokenStream
 
 	let outer_origin = decl_outer_origin(
 		&name,
-		all_but_system_modules.clone(),
+		all_but_system_modules,
 		&system_module,
 		&scrate,
 	)?;
@@ -136,7 +204,7 @@ fn construct_runtime_parsed(definition: RuntimeDefinition) -> Result<TokenStream
 
 fn decl_validate_unsigned<'a>(
 	runtime: &'a Ident,
-	module_declarations: impl Iterator<Item = &'a ModuleDeclaration>,
+	module_declarations: impl Iterator<Item = &'a Module>,
 	scrate: &'a TokenStream2,
 ) -> TokenStream2 {
 	let modules_tokens = module_declarations
@@ -154,7 +222,7 @@ fn decl_validate_unsigned<'a>(
 fn decl_outer_inherent<'a>(
 	block: &'a syn::TypePath,
 	unchecked_extrinsic: &'a syn::TypePath,
-	module_declarations: impl Iterator<Item = &'a ModuleDeclaration>,
+	module_declarations: impl Iterator<Item = &'a Module>,
 	scrate: &'a TokenStream2,
 ) -> TokenStream2 {
 	let modules_tokens = module_declarations.filter_map(|module_declaration| {
@@ -178,7 +246,7 @@ fn decl_outer_inherent<'a>(
 
 fn decl_outer_config<'a>(
 	runtime: &'a Ident,
-	module_declarations: impl Iterator<Item = &'a ModuleDeclaration>,
+	module_declarations: impl Iterator<Item = &'a Module>,
 	scrate: &'a TokenStream2,
 ) -> TokenStream2 {
 	let modules_tokens = module_declarations
@@ -216,7 +284,7 @@ fn decl_outer_config<'a>(
 
 fn decl_runtime_metadata<'a>(
 	runtime: &'a Ident,
-	module_declarations: impl Iterator<Item = &'a ModuleDeclaration>,
+	module_declarations: impl Iterator<Item = &'a Module>,
 	scrate: &'a TokenStream2,
 	extrinsic: &TypePath,
 ) -> TokenStream2 {
@@ -240,7 +308,12 @@ fn decl_runtime_metadata<'a>(
 				.as_ref()
 				.map(|name| quote!(<#name>))
 				.into_iter();
-			quote!(#module::Module #(#instance)* as #name with #(#filtered_names)* ,)
+
+			let index = module_declaration.index;
+
+			quote!(
+				#module::Module #(#instance)* as #name { index #index } with #(#filtered_names)*,
+			)
 		});
 	quote!(
 		#scrate::impl_runtime_metadata!{
@@ -252,7 +325,7 @@ fn decl_runtime_metadata<'a>(
 
 fn decl_outer_dispatch<'a>(
 	runtime: &'a Ident,
-	module_declarations: impl Iterator<Item = &'a ModuleDeclaration>,
+	module_declarations: impl Iterator<Item = &'a Module>,
 	scrate: &'a TokenStream2,
 ) -> TokenStream2 {
 	let modules_tokens = module_declarations
@@ -260,8 +333,10 @@ fn decl_outer_dispatch<'a>(
 		.map(|module_declaration| {
 			let module = &module_declaration.module;
 			let name = &module_declaration.name;
-			quote!(#module::#name)
+			let index = module_declaration.index.to_string();
+			quote!(#[codec(index = #index)] #module::#name)
 		});
+
 	quote!(
 		#scrate::impl_outer_dispatch! {
 			pub enum Call for #runtime where origin: Origin {
@@ -273,12 +348,12 @@ fn decl_outer_dispatch<'a>(
 
 fn decl_outer_origin<'a>(
 	runtime_name: &'a Ident,
-	module_declarations: impl Iterator<Item = &'a ModuleDeclaration>,
-	system_name: &'a Ident,
+	modules_except_system: impl Iterator<Item = &'a Module>,
+	system_module: &'a Module,
 	scrate: &'a TokenStream2,
 ) -> syn::Result<TokenStream2> {
 	let mut modules_tokens = TokenStream2::new();
-	for module_declaration in module_declarations {
+	for module_declaration in modules_except_system {
 		match module_declaration.find_part("Origin") {
 			Some(module_entry) => {
 				let module = &module_declaration.module;
@@ -292,16 +367,23 @@ fn decl_outer_origin<'a>(
 					);
 					return Err(syn::Error::new(module_declaration.name.span(), msg));
 				}
-				let tokens = quote!(#module #instance #generics ,);
+				let index = module_declaration.index.to_string();
+				let tokens = quote!(#[codec(index = #index)] #module #instance #generics,);
 				modules_tokens.extend(tokens);
 			}
 			None => {}
 		}
 	}
 
+	let system_name = &system_module.module;
+	let system_index = system_module.index.to_string();
+
 	Ok(quote!(
 		#scrate::impl_outer_origin! {
-			pub enum Origin for #runtime_name where system = #system_name {
+			pub enum Origin for #runtime_name where
+				system = #system_name,
+				system_index = #system_index
+			{
 				#modules_tokens
 			}
 		}
@@ -310,7 +392,7 @@ fn decl_outer_origin<'a>(
 
 fn decl_outer_event<'a>(
 	runtime_name: &'a Ident,
-	module_declarations: impl Iterator<Item = &'a ModuleDeclaration>,
+	module_declarations: impl Iterator<Item = &'a Module>,
 	scrate: &'a TokenStream2,
 ) -> syn::Result<TokenStream2> {
 	let mut modules_tokens = TokenStream2::new();
@@ -328,7 +410,9 @@ fn decl_outer_event<'a>(
 					);
 					return Err(syn::Error::new(module_declaration.name.span(), msg));
 				}
-				let tokens = quote!(#module #instance #generics ,);
+
+				let index = module_declaration.index.to_string();
+				let tokens = quote!(#[codec(index = #index)] #module #instance #generics,);
 				modules_tokens.extend(tokens);
 			}
 			None => {}
@@ -346,7 +430,7 @@ fn decl_outer_event<'a>(
 
 fn decl_all_modules<'a>(
 	runtime: &'a Ident,
-	module_declarations: impl Iterator<Item = &'a ModuleDeclaration>,
+	module_declarations: impl Iterator<Item = &'a Module>,
 ) -> TokenStream2 {
 	let mut types = TokenStream2::new();
 	let mut names = Vec::new();
@@ -379,13 +463,14 @@ fn decl_all_modules<'a>(
 }
 
 fn decl_pallet_runtime_setup(
-	module_declarations: &[ModuleDeclaration],
+	module_declarations: &[Module],
 	scrate: &TokenStream2,
 ) -> TokenStream2 {
 	let names = module_declarations.iter().map(|d| &d.name);
 	let names2 = module_declarations.iter().map(|d| &d.name);
 	let name_strings = module_declarations.iter().map(|d| d.name.to_string());
-	let indices = 0..module_declarations.len();
+	let indices = module_declarations.iter()
+		.map(|module| module.index as usize);
 
 	quote!(
 		/// Provides an implementation of `PalletInfo` to provide information
@@ -418,14 +503,6 @@ fn decl_pallet_runtime_setup(
 	)
 }
 
-fn find_system_module<'a>(
-	mut module_declarations: impl Iterator<Item = &'a ModuleDeclaration>,
-) -> Option<&'a Ident> {
-	module_declarations
-		.find(|decl| decl.name == SYSTEM_MODULE_NAME)
-		.map(|decl| &decl.module)
-}
-
 fn decl_integrity_test(scrate: &TokenStream2) -> TokenStream2 {
 	quote!(
 		#[cfg(test)]
diff --git a/frame/support/procedural/src/construct_runtime/parse.rs b/frame/support/procedural/src/construct_runtime/parse.rs
index c8481480baac5..4a45044d67f25 100644
--- a/frame/support/procedural/src/construct_runtime/parse.rs
+++ b/frame/support/procedural/src/construct_runtime/parse.rs
@@ -149,9 +149,11 @@ impl Parse for WhereDefinition {
 	}
 }
 
-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct ModuleDeclaration {
 	pub name: Ident,
+	/// Optional fixed index (e.g. `MyPallet ...  = 3,`)
+	pub index: Option<u8>,
 	pub module: Ident,
 	pub instance: Option<Ident>,
 	pub module_parts: Vec<ModulePart>,
@@ -175,32 +177,27 @@ impl Parse for ModuleDeclaration {
 		let _: Token![::] = input.parse()?;
 		let module_parts = parse_module_parts(input)?;
 
+		let index = if input.peek(Token![=]) {
+			input.parse::<Token![=]>()?;
+			let index = input.parse::<syn::LitInt>()?;
+			let index = index.base10_parse::<u8>()?;
+			Some(index)
+		} else {
+			None
+		};
+
 		let parsed = Self {
 			name,
 			module,
 			instance,
 			module_parts,
+			index,
 		};
 
 		Ok(parsed)
 	}
 }
 
-impl ModuleDeclaration {
-	/// Get resolved module parts
-	pub fn module_parts(&self) -> &[ModulePart] {
-		&self.module_parts
-	}
-
-	pub fn find_part(&self, name: &str) -> Option<&ModulePart> {
-		self.module_parts.iter().find(|part| part.name() == name)
-	}
-
-	pub fn exists_part(&self, name: &str) -> bool {
-		self.find_part(name).is_some()
-	}
-}
-
 /// Parse [`ModulePart`]'s from a braces enclosed list that is split by commas, e.g.
 ///
 /// `{ Call, Event }`
diff --git a/frame/support/procedural/src/lib.rs b/frame/support/procedural/src/lib.rs
index 060882d1123bf..bf87bd552fd06 100644
--- a/frame/support/procedural/src/lib.rs
+++ b/frame/support/procedural/src/lib.rs
@@ -252,13 +252,13 @@ pub fn decl_storage(input: TokenStream) -> TokenStream {
 ///         NodeBlock = runtime::Block,
 ///         UncheckedExtrinsic = UncheckedExtrinsic
 ///     {
-///         System: system::{Module, Call, Event<T>, Config<T>},
-///         Test: test::{Module, Call},
-///         Test2: test_with_long_module::{Module},
+///         System: system::{Module, Call, Event<T>, Config<T>} = 0,
+///         Test: test::{Module, Call} = 1,
+///         Test2: test_with_long_module::{Module, Event<T>},
 ///
 ///         // Module with instances
 ///         Test3_Instance1: test3::<Instance1>::{Module, Call, Storage, Event<T, I>, Config<T, I>, Origin<T, I>},
-///         Test3_DefaultInstance: test3::{Module, Call, Storage, Event<T>, Config<T>, Origin<T>},
+///         Test3_DefaultInstance: test3::{Module, Call, Storage, Event<T>, Config<T>, Origin<T>} = 4,
 ///     }
 /// )
 /// ```
@@ -279,6 +279,18 @@ pub fn decl_storage(input: TokenStream) -> TokenStream {
 /// - `Inherent` - If the module provides/can check inherents.
 /// - `ValidateUnsigned` - If the module validates unsigned extrinsics.
 ///
+/// `= $n` is an optional part allowing to define at which index the module variants in
+/// `OriginCaller`, `Call` and `Event` are encoded, and to define the ModuleToIndex value.
+///
+/// if `= $n` is not given, then index is resolved same as fieldless enum in Rust
+/// (i.e. incrementedly from previous index):
+/// ```nocompile
+/// module1 .. = 2,
+/// module2 .., // Here module2 is given index 3
+/// module3 .. = 0,
+/// module4 .., // Here module4 is given index 1
+/// ```
+///
 /// # Note
 ///
 /// The population of the genesis storage depends on the order of modules. So, if one of your
diff --git a/frame/support/src/dispatch.rs b/frame/support/src/dispatch.rs
index ca0a78d730b7c..02e03ec6e6d6d 100644
--- a/frame/support/src/dispatch.rs
+++ b/frame/support/src/dispatch.rs
@@ -1911,7 +1911,7 @@ macro_rules! impl_outer_dispatch {
 		$(#[$attr:meta])*
 		pub enum $call_type:ident for $runtime:ident where origin: $origin:ty {
 			$(
-				$module:ident::$camelcase:ident,
+				$( #[codec(index = $index:tt)] )? $module:ident::$camelcase:ident,
 			)*
 		}
 	) => {
@@ -1924,6 +1924,7 @@ macro_rules! impl_outer_dispatch {
 		)]
 		pub enum $call_type {
 			$(
+				$( #[codec(index = $index)] )?
 				$camelcase ( $crate::dispatch::CallableCallFor<$camelcase, $runtime> )
 			,)*
 		}
diff --git a/frame/support/src/event.rs b/frame/support/src/event.rs
index 1184b379f4446..0f889f97f40a0 100644
--- a/frame/support/src/event.rs
+++ b/frame/support/src/event.rs
@@ -346,7 +346,7 @@ macro_rules! impl_outer_event {
 			$name;
 			$runtime;
 			Modules { $( $rest_events )* };
-			;
+			{};
 		);
 	};
 	// Generic + Instance
@@ -355,17 +355,17 @@ macro_rules! impl_outer_event {
 		$name:ident;
 		$runtime:ident;
 		Modules {
-			$module:ident $instance:ident<T>,
+			$( #[codec(index = $index:tt)] )? $module:ident $instance:ident<T>,
 			$( $rest_event_generic_instance:tt )*
 		};
-		$( $module_name:ident::Event $( <$generic_param:ident> )? $( { $generic_instance:ident } )?, )*;
+		{ $( $parsed:tt )* };
 	) => {
 		$crate::impl_outer_event!(
 			$( #[$attr] )*;
 			$name;
 			$runtime;
 			Modules { $( $rest_event_generic_instance )* };
-			$( $module_name::Event $( <$generic_param> )? $( { $generic_instance } )?, )* $module::Event<$runtime>{ $instance },;
+			{ $( $parsed )* $module::Event<$runtime>{ $instance } index { $( $index )? }, };
 		);
 	};
 	// Instance
@@ -374,17 +374,17 @@ macro_rules! impl_outer_event {
 		$name:ident;
 		$runtime:ident;
 		Modules {
-			$module:ident $instance:ident,
+			$( #[codec(index = $index:tt)] )? $module:ident $instance:ident,
 			$( $rest_event_instance:tt )*
 		};
-		$( $module_name:ident::Event $( <$generic_param:ident> )? $( { $generic_instance:ident } )?, )*;
+		{ $( $parsed:tt )* };
 	) => {
 		$crate::impl_outer_event!(
 			$( #[$attr] )*;
 			$name;
 			$runtime;
 			Modules { $( $rest_event_instance )* };
-			$( $module_name::Event $( <$generic_param> )* $( { $generic_instance } )?, )* $module::Event { $instance },;
+			{ $( $parsed )* $module::Event { $instance } index { $( $index )? }, };
 		);
 	};
 	// Generic
@@ -393,17 +393,17 @@ macro_rules! impl_outer_event {
 		$name:ident;
 		$runtime:ident;
 		Modules {
-			$module:ident<T>,
+			$( #[codec(index = $index:tt)] )? $module:ident<T>,
 			$( $rest_event_generic:tt )*
 		};
-		$( $module_name:ident::Event $( <$generic_param:ident> )? $( { $generic_instance:ident } )?, )*;
+		{ $( $parsed:tt )* };
 	) => {
 		$crate::impl_outer_event!(
 			$( #[$attr] )*;
 			$name;
 			$runtime;
 			Modules { $( $rest_event_generic )* };
-			$( $module_name::Event $( <$generic_param> )? $( { $generic_instance } )?, )* $module::Event<$runtime>,;
+			{ $( $parsed )* $module::Event<$runtime> index { $( $index )? }, };
 		);
 	};
 	// No Generic and no Instance
@@ -412,17 +412,17 @@ macro_rules! impl_outer_event {
 		$name:ident;
 		$runtime:ident;
 		Modules {
-			$module:ident,
+			$( #[codec(index = $index:tt)] )? $module:ident,
 			$( $rest_event_no_generic_no_instance:tt )*
 		};
-		$( $module_name:ident::Event $( <$generic_param:ident> )? $( { $generic_instance:ident } )?, )*;
+		{ $( $parsed:tt )* };
 	) => {
 		$crate::impl_outer_event!(
 			$( #[$attr] )*;
 			$name;
 			$runtime;
 			Modules { $( $rest_event_no_generic_no_instance )* };
-			$( $module_name::Event $( <$generic_param> )? $( { $generic_instance } )?, )* $module::Event,;
+			{ $( $parsed )* $module::Event index { $( $index )? }, };
 		);
 	};
 
@@ -432,7 +432,14 @@ macro_rules! impl_outer_event {
 		$name:ident;
 		$runtime:ident;
 		Modules {};
-		$( $module_name:ident::Event $( <$generic_param:ident> )? $( { $generic_instance:ident } )?, )*;
+		{
+			$(
+				$module_name:ident::Event
+				$( <$generic_param:ident> )?
+				$( { $generic_instance:ident } )?
+				index { $( $index:tt )? },
+			)*
+		};
 	) => {
 		$crate::paste::item! {
 			#[derive(
@@ -445,6 +452,7 @@ macro_rules! impl_outer_event {
 			#[allow(non_camel_case_types)]
 			pub enum $name {
 				$(
+					$( #[codec(index = $index)] )?
 					[< $module_name $(_ $generic_instance )? >](
 						$module_name::Event < $( $generic_param )? $(, $module_name::$generic_instance )? >
 					),
@@ -697,7 +705,7 @@ mod tests {
 		pub enum TestEventSystemRenamed for TestRuntime2 {
 			system_renamed,
 			event_module<T>,
-			event_module2<T>,
+			#[codec(index = "5")] event_module2<T>,
 			event_module3,
 		}
 	}
@@ -796,4 +804,22 @@ mod tests {
 	fn outer_event_metadata() {
 		assert_eq!(EXPECTED_METADATA, TestRuntime::outer_event_metadata());
 	}
+
+	#[test]
+	fn test_codec() {
+		let runtime_1_event_module_2 = TestEvent::event_module2(
+			event_module2::Event::<TestRuntime>::TestEvent(3)
+		);
+		assert_eq!(runtime_1_event_module_2.encode()[0], 2);
+
+		let runtime_2_event_module_2 = TestEventSystemRenamed::event_module2(
+			event_module2::Event::<TestRuntime2>::TestEvent(3)
+		);
+		assert_eq!(runtime_2_event_module_2.encode()[0], 5);
+		
+		let runtime_2_event_module_3 = TestEventSystemRenamed::event_module3(
+			event_module3::Event::HiEvent
+		);
+		assert_eq!(runtime_2_event_module_3.encode()[0], 3);
+	}
 }
diff --git a/frame/support/src/metadata.rs b/frame/support/src/metadata.rs
index 8d3b5fb527af7..9ae1d6ce663d5 100644
--- a/frame/support/src/metadata.rs
+++ b/frame/support/src/metadata.rs
@@ -51,9 +51,9 @@ pub use frame_metadata::{
 /// struct Runtime;
 /// frame_support::impl_runtime_metadata! {
 ///     for Runtime with modules where Extrinsic = UncheckedExtrinsic
-///         module0::Module as Module0 with,
-///         module1::Module as Module1 with,
-///         module2::Module as Module2 with Storage,
+///         module0::Module as Module0 { index 0 } with,
+///         module1::Module as Module1 { index 1 } with,
+///         module2::Module as Module2 { index 2 } with Storage,
 /// };
 /// ```
 ///
@@ -91,13 +91,17 @@ macro_rules! __runtime_modules_to_metadata {
 	(
 		$runtime: ident;
 		$( $metadata:expr ),*;
-		$mod:ident::$module:ident $( < $instance:ident > )? as $name:ident $(with)+ $($kw:ident)*,
+		$mod:ident::$module:ident $( < $instance:ident > )? as $name:ident
+			{ index $index:tt }
+			$(with)+ $($kw:ident)*
+		,
 		$( $rest:tt )*
 	) => {
 		$crate::__runtime_modules_to_metadata!(
 			$runtime;
 			$( $metadata, )* $crate::metadata::ModuleMetadata {
 				name: $crate::metadata::DecodeDifferent::Encode(stringify!($name)),
+				index: $index,
 				storage: $crate::__runtime_modules_to_metadata_calls_storage!(
 					$mod, $module $( <$instance> )?, $runtime, $(with $kw)*
 				),
@@ -449,9 +453,9 @@ mod tests {
 
 	impl_runtime_metadata!(
 		for TestRuntime with modules where Extrinsic = TestExtrinsic
-			system::Module as System with Event,
-			event_module::Module as Module with Event Call,
-			event_module2::Module as Module2 with Event Storage Call,
+			system::Module as System { index 0 } with Event,
+			event_module::Module as Module { index 1 } with Event Call,
+			event_module2::Module as Module2 { index 2 } with Event Storage Call,
 	);
 
 	struct ConstantBlockNumberByteGetter;
@@ -481,6 +485,7 @@ mod tests {
 			modules: DecodeDifferent::Encode(&[
 				ModuleMetadata {
 					name: DecodeDifferent::Encode("System"),
+					index: 0,
 					storage: None,
 					calls: None,
 					event: Some(DecodeDifferent::Encode(
@@ -524,6 +529,7 @@ mod tests {
 				},
 				ModuleMetadata {
 					name: DecodeDifferent::Encode("Module"),
+					index: 1,
 					storage: None,
 					calls: Some(
 						DecodeDifferent::Encode(FnEncode(|| &[
@@ -559,6 +565,7 @@ mod tests {
 				},
 				ModuleMetadata {
 					name: DecodeDifferent::Encode("Module2"),
+					index: 2,
 					storage: Some(DecodeDifferent::Encode(
 						FnEncode(|| StorageMetadata {
 							prefix: DecodeDifferent::Encode("TestStorage"),
diff --git a/frame/support/src/origin.rs b/frame/support/src/origin.rs
index df75f8dc65645..e4052337a0141 100644
--- a/frame/support/src/origin.rs
+++ b/frame/support/src/origin.rs
@@ -41,7 +41,10 @@ macro_rules! impl_outer_origin {
 
 	(
 		$(#[$attr:meta])*
-		pub enum $name:ident for $runtime:ident where system = $system:ident {
+		pub enum $name:ident for $runtime:ident where
+			system = $system:ident
+			$(, system_index = $system_index:tt)?
+		{
 			$( $rest_with_system:tt )*
 		}
 	) => {
@@ -52,6 +55,7 @@ macro_rules! impl_outer_origin {
 				[< $name Caller >];
 				$runtime;
 				$system;
+				system_index { $( $system_index )? };
 				Modules { $( $rest_with_system )* };
 			);
 		}
@@ -64,8 +68,9 @@ macro_rules! impl_outer_origin {
 		$caller_name:ident;
 		$runtime:ident;
 		$system:ident;
+		system_index { $( $system_index:tt )? };
 		Modules {
-			$module:ident $instance:ident <T>
+			$( #[codec(index = $index:tt)] )? $module:ident $instance:ident <T>
 			$(, $( $rest_module:tt )* )?
 		};
 		$( $parsed:tt )*
@@ -76,8 +81,9 @@ macro_rules! impl_outer_origin {
 			$caller_name;
 			$runtime;
 			$system;
+			system_index { $( $system_index )? };
 			Modules { $( $( $rest_module )* )? };
-			$( $parsed )* $module <$runtime> { $instance },
+			$( $parsed )* $module <$runtime> { $instance } index { $( $index )? },
 		);
 	};
 
@@ -88,8 +94,9 @@ macro_rules! impl_outer_origin {
 		$caller_name:ident;
 		$runtime:ident;
 		$system:ident;
+		system_index { $( $system_index:tt )? };
 		Modules {
-			$module:ident $instance:ident
+			$( #[codec(index = $index:tt )] )? $module:ident $instance:ident
 			$(, $rest_module:tt )*
 		};
 		$( $parsed:tt )*
@@ -100,8 +107,9 @@ macro_rules! impl_outer_origin {
 			$caller_name;
 			$runtime;
 			$system;
+			system_index { $( $system_index )? };
 			Modules { $( $rest_module )* };
-			$( $parsed )* $module { $instance },
+			$( $parsed )* $module { $instance } index { $( $index )? },
 		);
 	};
 
@@ -112,8 +120,9 @@ macro_rules! impl_outer_origin {
 		$caller_name:ident;
 		$runtime:ident;
 		$system:ident;
+		system_index { $( $system_index:tt )? };
 		Modules {
-			$module:ident <T>
+			$( #[codec(index = $index:tt )] )? $module:ident <T>
 			$(, $( $rest_module:tt )* )?
 		};
 		$( $parsed:tt )*
@@ -124,8 +133,9 @@ macro_rules! impl_outer_origin {
 			$caller_name;
 			$runtime;
 			$system;
+			system_index { $( $system_index )? };
 			Modules { $( $( $rest_module )* )? };
-			$( $parsed )* $module <$runtime>,
+			$( $parsed )* $module <$runtime> index { $( $index )? },
 		);
 	};
 
@@ -136,8 +146,9 @@ macro_rules! impl_outer_origin {
 		$caller_name:ident;
 		$runtime:ident;
 		$system:ident;
+		system_index { $( $system_index:tt )? };
 		Modules {
-			$module:ident
+			$( #[codec(index = $index:tt )] )? $module:ident
 			$(, $( $rest_module:tt )* )?
 		};
 		$( $parsed:tt )*
@@ -148,8 +159,9 @@ macro_rules! impl_outer_origin {
 			$caller_name;
 			$runtime;
 			$system;
+			system_index { $( $system_index )? };
 			Modules { $( $( $rest_module )* )? };
-			$( $parsed )* $module,
+			$( $parsed )* $module index { $( $index )? },
 		);
 	};
 
@@ -160,8 +172,14 @@ macro_rules! impl_outer_origin {
 		$caller_name:ident;
 		$runtime:ident;
 		$system:ident;
+		system_index { $( $system_index:tt )? };
 		Modules { };
-		$( $module:ident $( < $generic:ident > )? $( { $generic_instance:ident } )? ,)*
+		$(
+			$module:ident
+			$( < $generic:ident > )?
+			$( { $generic_instance:ident } )?
+			index { $( $index:tt )? },
+		)*
 	) => {
 		// WARNING: All instance must hold the filter `frame_system::Trait::BaseCallFilter`, except
 		// when caller is system Root. One can use `OriginTrait::reset_filter` to do so.
@@ -233,8 +251,10 @@ macro_rules! impl_outer_origin {
 			$(#[$attr])*
 			#[allow(non_camel_case_types)]
 			pub enum $caller_name {
+				$( #[codec(index = $system_index)] )?
 				system($system::Origin<$runtime>),
 				$(
+					$( #[codec(index = $index)] )?
 					[< $module $( _ $generic_instance )? >]
 					($module::Origin < $( $generic, )? $( $module::$generic_instance )? > ),
 				)*
@@ -442,6 +462,13 @@ mod tests {
 		pub enum OriginEmpty for TestRuntime where system = frame_system {}
 	);
 
+	impl_outer_origin!(
+		pub enum OriginIndices for TestRuntime where system = frame_system, system_index = "11" {
+			origin_with_generic<T>,
+			#[codec(index = "10")] origin_without_generic,
+		}
+	);
+
 	#[test]
 	fn test_default_filter() {
 		assert_eq!(OriginWithSystem::root().filter_call(&0), true);
@@ -472,4 +499,20 @@ mod tests {
 		assert_eq!(origin.filter_call(&0), true);
 		assert_eq!(origin.filter_call(&1), false);
 	}
+
+	#[test]
+	fn test_codec() {
+		use codec::Encode;
+		assert_eq!(OriginIndices::root().caller.encode()[0], 11);
+		let without_generic_variant = OriginIndicesCaller::origin_without_generic(
+			origin_without_generic::Origin
+		);
+		assert_eq!(without_generic_variant.encode()[0], 10);
+
+		assert_eq!(OriginWithoutSystem::root().caller.encode()[0], 0);
+		let without_generic_variant = OriginWithoutSystemCaller::origin_without_generic(
+			origin_without_generic::Origin
+		);
+		assert_eq!(without_generic_variant.encode()[0], 1);
+	}
 }
diff --git a/frame/support/test/Cargo.toml b/frame/support/test/Cargo.toml
index 7c839e4462ad1..e516bf8a65f6a 100644
--- a/frame/support/test/Cargo.toml
+++ b/frame/support/test/Cargo.toml
@@ -24,6 +24,7 @@ sp-std = { version = "2.0.0-rc6", default-features = false, path = "../../../pri
 trybuild = "1.0.33"
 pretty_assertions = "0.6.1"
 rustversion = "1.0.0"
+frame-metadata = { version = "12.0.0-rc6", default-features = false, path = "../../metadata" }
 
 [features]
 default = ["std"]
diff --git a/frame/support/test/tests/construct_runtime.rs b/frame/support/test/tests/construct_runtime.rs
index 5596943031148..9a17e44dbef4c 100644
--- a/frame/support/test/tests/construct_runtime.rs
+++ b/frame/support/test/tests/construct_runtime.rs
@@ -50,6 +50,17 @@ mod module1 {
 		}
 	}
 
+	#[derive(Clone, PartialEq, Eq, Debug, codec::Encode, codec::Decode)]
+	pub struct Origin<T, I: Instance = DefaultInstance>(pub core::marker::PhantomData::<(T, I)>);
+
+	frame_support::decl_event! {
+		pub enum Event<T, I: Instance = DefaultInstance> where
+			<T as system::Trait>::AccountId
+		{
+			A(AccountId),
+		}
+	}
+
 	frame_support::decl_error! {
 		pub enum Error for Module<T: Trait<I>, I: Instance> {
 			Something
@@ -81,6 +92,15 @@ mod module2 {
 		}
 	}
 
+	#[derive(Clone, PartialEq, Eq, Debug, codec::Encode, codec::Decode)]
+	pub struct Origin;
+
+	frame_support::decl_event! {
+		pub enum Event {
+			A,
+		}
+	}
+
 	frame_support::decl_error! {
 		pub enum Error for Module<T: Trait> {
 			Something
@@ -92,8 +112,7 @@ mod module2 {
 	}
 }
 
-impl module1::Trait<module1::Instance1> for Runtime {}
-impl module1::Trait<module1::Instance2> for Runtime {}
+impl<I> module1::Trait<I> for Runtime {}
 impl module2::Trait for Runtime {}
 
 pub type Signature = sr25519::Signature;
@@ -118,10 +137,17 @@ frame_support::construct_runtime!(
 		NodeBlock = Block,
 		UncheckedExtrinsic = UncheckedExtrinsic
 	{
-		System: system::{Module, Call, Event<T>},
-		Module1_1: module1::<Instance1>::{Module, Call, Storage},
-		Module2: module2::{Module, Call, Storage},
-		Module1_2: module1::<Instance2>::{Module, Call, Storage},
+		System: system::{Module, Call, Event<T>, Origin<T>} = 30,
+		Module1_1: module1::<Instance1>::{Module, Call, Storage, Event<T>, Origin<T>},
+		Module2: module2::{Module, Call, Storage, Event, Origin},
+		Module1_2: module1::<Instance2>::{Module, Call, Storage, Event<T>, Origin<T>},
+		Module1_3: module1::<Instance3>::{Module, Storage} = 6,
+		Module1_4: module1::<Instance4>::{Module, Call} = 3,
+		Module1_5: module1::<Instance5>::{Module, Event<T>},
+		Module1_6: module1::<Instance6>::{Module, Call, Storage, Event<T>, Origin<T>} = 1,
+		Module1_7: module1::<Instance7>::{Module, Call, Storage, Event<T>, Origin<T>},
+		Module1_8: module1::<Instance8>::{Module, Call, Storage, Event<T>, Origin<T>} = 12,
+		Module1_9: module1::<Instance9>::{Module, Call, Storage, Event<T>, Origin<T>},
 	}
 );
 
@@ -130,27 +156,47 @@ pub type Block = generic::Block<Header, UncheckedExtrinsic>;
 pub type UncheckedExtrinsic = generic::UncheckedExtrinsic<u32, Call, Signature, ()>;
 
 #[test]
-fn check_module1_1_error_type() {
+fn check_modules_error_type() {
 	assert_eq!(
 		Module1_1::fail(system::Origin::<Runtime>::Root.into()),
-		Err(DispatchError::Module { index: 1, error: 0, message: Some("Something") }),
+		Err(DispatchError::Module { index: 31, error: 0, message: Some("Something") }),
+	);
+	assert_eq!(
+		Module2::fail(system::Origin::<Runtime>::Root.into()),
+		Err(DispatchError::Module { index: 32, error: 0, message: Some("Something") }),
 	);
-}
-
-#[test]
-fn check_module1_2_error_type() {
 	assert_eq!(
 		Module1_2::fail(system::Origin::<Runtime>::Root.into()),
+		Err(DispatchError::Module { index: 33, error: 0, message: Some("Something") }),
+	);
+	assert_eq!(
+		Module1_3::fail(system::Origin::<Runtime>::Root.into()),
+		Err(DispatchError::Module { index: 6, error: 0, message: Some("Something") }),
+	);
+	assert_eq!(
+		Module1_4::fail(system::Origin::<Runtime>::Root.into()),
 		Err(DispatchError::Module { index: 3, error: 0, message: Some("Something") }),
 	);
-}
-
-#[test]
-fn check_module2_error_type() {
 	assert_eq!(
-		Module2::fail(system::Origin::<Runtime>::Root.into()),
+		Module1_5::fail(system::Origin::<Runtime>::Root.into()),
+		Err(DispatchError::Module { index: 4, error: 0, message: Some("Something") }),
+	);
+	assert_eq!(
+		Module1_6::fail(system::Origin::<Runtime>::Root.into()),
+		Err(DispatchError::Module { index: 1, error: 0, message: Some("Something") }),
+	);
+	assert_eq!(
+		Module1_7::fail(system::Origin::<Runtime>::Root.into()),
 		Err(DispatchError::Module { index: 2, error: 0, message: Some("Something") }),
 	);
+	assert_eq!(
+		Module1_8::fail(system::Origin::<Runtime>::Root.into()),
+		Err(DispatchError::Module { index: 12, error: 0, message: Some("Something") }),
+	);
+	assert_eq!(
+		Module1_9::fail(system::Origin::<Runtime>::Root.into()),
+		Err(DispatchError::Module { index: 13, error: 0, message: Some("Something") }),
+	);
 }
 
 #[test]
@@ -159,14 +205,340 @@ fn integrity_test_works() {
 	assert_eq!(INTEGRITY_TEST_EXEC.with(|i| *i.borrow()), 1);
 }
 
+#[test]
+fn origin_codec() {
+	use codec::Encode;
+
+	let origin = OriginCaller::system(system::RawOrigin::None);
+	assert_eq!(origin.encode()[0], 30);
+
+	let origin = OriginCaller::module1_Instance1(module1::Origin(Default::default()));
+	assert_eq!(origin.encode()[0], 31);
+
+	let origin = OriginCaller::module2(module2::Origin);
+	assert_eq!(origin.encode()[0], 32);
+
+	let origin = OriginCaller::module1_Instance2(module1::Origin(Default::default()));
+	assert_eq!(origin.encode()[0], 33);
+
+	let origin = OriginCaller::module1_Instance6(module1::Origin(Default::default()));
+	assert_eq!(origin.encode()[0], 1);
+
+	let origin = OriginCaller::module1_Instance7(module1::Origin(Default::default()));
+	assert_eq!(origin.encode()[0], 2);
+
+	let origin = OriginCaller::module1_Instance8(module1::Origin(Default::default()));
+	assert_eq!(origin.encode()[0], 12);
+
+	let origin = OriginCaller::module1_Instance9(module1::Origin(Default::default()));
+	assert_eq!(origin.encode()[0], 13);
+}
+
+#[test]
+fn event_codec() {
+	use codec::Encode;
+
+	let event = system::Event::<Runtime>::ExtrinsicSuccess;
+	assert_eq!(Event::from(event).encode()[0], 30);
+
+	let event = module1::Event::<Runtime, module1::Instance1>::A(Default::default());
+	assert_eq!(Event::from(event).encode()[0], 31);
+
+	let event = module2::Event::A;
+	assert_eq!(Event::from(event).encode()[0], 32);
+
+	let event = module1::Event::<Runtime, module1::Instance2>::A(Default::default());
+	assert_eq!(Event::from(event).encode()[0], 33);
+
+	let event = module1::Event::<Runtime, module1::Instance5>::A(Default::default());
+	assert_eq!(Event::from(event).encode()[0], 4);
+
+	let event = module1::Event::<Runtime, module1::Instance6>::A(Default::default());
+	assert_eq!(Event::from(event).encode()[0], 1);
+
+	let event = module1::Event::<Runtime, module1::Instance7>::A(Default::default());
+	assert_eq!(Event::from(event).encode()[0], 2);
+
+	let event = module1::Event::<Runtime, module1::Instance8>::A(Default::default());
+	assert_eq!(Event::from(event).encode()[0], 12);
+
+	let event = module1::Event::<Runtime, module1::Instance9>::A(Default::default());
+	assert_eq!(Event::from(event).encode()[0], 13);
+}
+
+#[test]
+fn call_codec() {
+	use codec::Encode;
+	assert_eq!(Call::System(system::Call::noop()).encode()[0], 30);
+	assert_eq!(Call::Module1_1(module1::Call::fail()).encode()[0], 31);
+	assert_eq!(Call::Module2(module2::Call::fail()).encode()[0], 32);
+	assert_eq!(Call::Module1_2(module1::Call::fail()).encode()[0], 33);
+	assert_eq!(Call::Module1_4(module1::Call::fail()).encode()[0], 3);
+	assert_eq!(Call::Module1_6(module1::Call::fail()).encode()[0], 1);
+	assert_eq!(Call::Module1_7(module1::Call::fail()).encode()[0], 2);
+	assert_eq!(Call::Module1_8(module1::Call::fail()).encode()[0], 12);
+	assert_eq!(Call::Module1_9(module1::Call::fail()).encode()[0], 13);
+}
+
+#[test]
+fn test_metadata() {
+	use frame_metadata::*;
+	let expected_metadata: RuntimeMetadataLastVersion = RuntimeMetadataLastVersion {
+		modules: DecodeDifferent::Encode(&[
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("System"),
+				storage: None,
+				calls: Some(DecodeDifferent::Encode(FnEncode(|| &[FunctionMetadata {
+					name: DecodeDifferent::Encode("noop"),
+					arguments: DecodeDifferent::Encode(&[]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				event: Some(DecodeDifferent::Encode(FnEncode(|| &[
+					EventMetadata {
+						name: DecodeDifferent::Encode("ExtrinsicSuccess"),
+						arguments: DecodeDifferent::Encode(&[]),
+						documentation: DecodeDifferent::Encode(&[]),
+					},
+					EventMetadata {
+						name: DecodeDifferent::Encode("ExtrinsicFailed"),
+						arguments: DecodeDifferent::Encode(&[]),
+						documentation: DecodeDifferent::Encode(&[]),
+					},
+					EventMetadata {
+						name: DecodeDifferent::Encode("Ignore"),
+						arguments: DecodeDifferent::Encode(&["BlockNumber"]),
+						documentation: DecodeDifferent::Encode(&[]),
+					},
+				]))),
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+				index: 30,
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module1_1"),
+				storage: Some(DecodeDifferent::Encode(FnEncode(|| StorageMetadata {
+					prefix: DecodeDifferent::Encode("Instance1Module"),
+					entries: DecodeDifferent::Encode(&[]),
+				}))),
+				calls: Some(DecodeDifferent::Encode(FnEncode(|| &[
+					FunctionMetadata {
+						name: DecodeDifferent::Encode("fail"),
+						arguments: DecodeDifferent::Encode(&[]),
+						documentation: DecodeDifferent::Encode(&[]),
+					},
+				]))),
+				event: Some(DecodeDifferent::Encode(FnEncode(|| &[EventMetadata {
+					name: DecodeDifferent::Encode("A"),
+					arguments: DecodeDifferent::Encode(&["AccountId"]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+				index: 31,
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module2"),
+				storage: Some(DecodeDifferent::Encode(FnEncode(|| StorageMetadata {
+					prefix: DecodeDifferent::Encode("Module"),
+					entries: DecodeDifferent::Encode(&[]),
+				}))),
+				calls: Some(DecodeDifferent::Encode(FnEncode(|| &[
+					FunctionMetadata {
+						name: DecodeDifferent::Encode("fail"),
+						arguments: DecodeDifferent::Encode(&[]),
+						documentation: DecodeDifferent::Encode(&[]),
+					},
+				]))),
+				event: Some(DecodeDifferent::Encode(FnEncode(|| &[
+					EventMetadata {
+						name: DecodeDifferent::Encode("A"),
+						arguments: DecodeDifferent::Encode(&[]),
+						documentation: DecodeDifferent::Encode(&[]),
+					},
+				]))),
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+				index: 32,
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module1_2"),
+				storage: Some(DecodeDifferent::Encode(FnEncode(|| StorageMetadata {
+					prefix: DecodeDifferent::Encode("Instance2Module"),
+					entries: DecodeDifferent::Encode(&[]),
+				}))),
+				calls: Some(DecodeDifferent::Encode(FnEncode(|| &[FunctionMetadata {
+					name: DecodeDifferent::Encode("fail"),
+					arguments: DecodeDifferent::Encode(&[]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				event: Some(DecodeDifferent::Encode(FnEncode(|| &[EventMetadata {
+					name: DecodeDifferent::Encode("A"),
+					arguments: DecodeDifferent::Encode(&["AccountId"]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+				index: 33,
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module1_3"),
+				storage: Some(DecodeDifferent::Encode(FnEncode(|| StorageMetadata {
+					prefix: DecodeDifferent::Encode("Instance3Module"),
+					entries: DecodeDifferent::Encode(&[]),
+				}))),
+				calls: None,
+				event: None,
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+				index: 6,
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module1_4"),
+				storage: None,
+				calls: Some(DecodeDifferent::Encode(FnEncode(|| &[FunctionMetadata {
+					name: DecodeDifferent::Encode("fail"),
+					arguments: DecodeDifferent::Encode(&[]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				event: None,
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+				index: 3,
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module1_5"),
+				storage: None,
+				calls: None,
+				event: Some(DecodeDifferent::Encode(FnEncode(|| &[EventMetadata {
+					name: DecodeDifferent::Encode("A"),
+					arguments: DecodeDifferent::Encode(&["AccountId"]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+				index: 4,
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module1_6"),
+				storage: Some(DecodeDifferent::Encode(FnEncode(|| StorageMetadata {
+					prefix: DecodeDifferent::Encode("Instance6Module"),
+					entries: DecodeDifferent::Encode(&[]),
+				}))),
+				calls: Some(DecodeDifferent::Encode(FnEncode(|| &[FunctionMetadata {
+					name: DecodeDifferent::Encode("fail"),
+					arguments: DecodeDifferent::Encode(&[]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				event: Some(DecodeDifferent::Encode(FnEncode(|| &[EventMetadata {
+					name: DecodeDifferent::Encode("A"),
+					arguments: DecodeDifferent::Encode(&["AccountId"]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+				index: 1,
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module1_7"),
+				storage: Some(DecodeDifferent::Encode(FnEncode(|| StorageMetadata {
+					prefix: DecodeDifferent::Encode("Instance7Module"),
+					entries: DecodeDifferent::Encode(&[]),
+				}))),
+				calls: Some(DecodeDifferent::Encode(FnEncode(|| &[FunctionMetadata {
+					name: DecodeDifferent::Encode("fail"),
+					arguments: DecodeDifferent::Encode(&[]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				event: Some(DecodeDifferent::Encode(FnEncode(|| &[EventMetadata {
+					name: DecodeDifferent::Encode("A"),
+					arguments: DecodeDifferent::Encode(&["AccountId"]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+				index: 2,
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module1_8"),
+				storage: Some(DecodeDifferent::Encode(FnEncode(|| StorageMetadata {
+					prefix: DecodeDifferent::Encode("Instance8Module"),
+					entries: DecodeDifferent::Encode(&[]),
+				}))),
+				calls: Some(DecodeDifferent::Encode(FnEncode(|| &[FunctionMetadata {
+					name: DecodeDifferent::Encode("fail"),
+					arguments: DecodeDifferent::Encode(&[]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				event: Some(DecodeDifferent::Encode(FnEncode(|| &[EventMetadata {
+					name: DecodeDifferent::Encode("A"),
+					arguments: DecodeDifferent::Encode(&["AccountId"]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+				index: 12,
+			},
+			ModuleMetadata {
+				name: DecodeDifferent::Encode("Module1_9"),
+				storage: Some(DecodeDifferent::Encode(FnEncode(|| StorageMetadata {
+					prefix: DecodeDifferent::Encode("Instance9Module"),
+					entries: DecodeDifferent::Encode(&[]),
+				}))),
+				calls: Some(DecodeDifferent::Encode(FnEncode(|| &[FunctionMetadata {
+					name: DecodeDifferent::Encode("fail"),
+					arguments: DecodeDifferent::Encode(&[]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				event: Some(DecodeDifferent::Encode(FnEncode(|| &[EventMetadata {
+					name: DecodeDifferent::Encode("A"),
+					arguments: DecodeDifferent::Encode(&["AccountId"]),
+					documentation: DecodeDifferent::Encode(&[]),
+				}]))),
+				constants: DecodeDifferent::Encode(FnEncode(|| &[])),
+				errors: DecodeDifferent::Encode(FnEncode(|| &[])),
+				index: 13,
+			},
+		]),
+		extrinsic: ExtrinsicMetadata {
+			version: 4,
+			signed_extensions: vec![DecodeDifferent::Encode("UnitSignedExtension")],
+		},
+	};
+	pretty_assertions::assert_eq!(Runtime::metadata().1, RuntimeMetadata::V12(expected_metadata));
+}
+
 #[test]
 fn pallet_in_runtime_is_correct() {
-	assert_eq!(PalletInfo::index::<System>().unwrap(), 0);
+	assert_eq!(PalletInfo::index::<System>().unwrap(), 30);
 	assert_eq!(PalletInfo::name::<System>().unwrap(), "System");
 
-	assert_eq!(PalletInfo::index::<Module1_2>().unwrap(), 3);
-	assert_eq!(PalletInfo::name::<Module1_2>().unwrap(), "Module1_2");
+	assert_eq!(PalletInfo::index::<Module1_1>().unwrap(), 31);
+	assert_eq!(PalletInfo::name::<Module1_1>().unwrap(), "Module1_1");
 
-	assert_eq!(PalletInfo::index::<Module2>().unwrap(), 2);
+	assert_eq!(PalletInfo::index::<Module2>().unwrap(), 32);
 	assert_eq!(PalletInfo::name::<Module2>().unwrap(), "Module2");
+
+	assert_eq!(PalletInfo::index::<Module1_2>().unwrap(), 33);
+	assert_eq!(PalletInfo::name::<Module1_2>().unwrap(), "Module1_2");
+
+	assert_eq!(PalletInfo::index::<Module1_3>().unwrap(), 6);
+	assert_eq!(PalletInfo::name::<Module1_3>().unwrap(), "Module1_3");
+
+	assert_eq!(PalletInfo::index::<Module1_4>().unwrap(), 3);
+	assert_eq!(PalletInfo::name::<Module1_4>().unwrap(), "Module1_4");
+
+	assert_eq!(PalletInfo::index::<Module1_5>().unwrap(), 4);
+	assert_eq!(PalletInfo::name::<Module1_5>().unwrap(), "Module1_5");
+
+	assert_eq!(PalletInfo::index::<Module1_6>().unwrap(), 1);
+	assert_eq!(PalletInfo::name::<Module1_6>().unwrap(), "Module1_6");
+
+	assert_eq!(PalletInfo::index::<Module1_7>().unwrap(), 2);
+	assert_eq!(PalletInfo::name::<Module1_7>().unwrap(), "Module1_7");
+
+	assert_eq!(PalletInfo::index::<Module1_8>().unwrap(), 12);
+	assert_eq!(PalletInfo::name::<Module1_8>().unwrap(), "Module1_8");
+
+	assert_eq!(PalletInfo::index::<Module1_9>().unwrap(), 13);
+	assert_eq!(PalletInfo::name::<Module1_9>().unwrap(), "Module1_9");
 }
diff --git a/frame/support/test/tests/construct_runtime_ui/conflicting_index.rs b/frame/support/test/tests/construct_runtime_ui/conflicting_index.rs
new file mode 100644
index 0000000000000..a48b4bd097039
--- /dev/null
+++ b/frame/support/test/tests/construct_runtime_ui/conflicting_index.rs
@@ -0,0 +1,14 @@
+use frame_support::construct_runtime;
+
+construct_runtime! {
+	pub enum Runtime where
+		UncheckedExtrinsic = UncheckedExtrinsic,
+		Block = Block,
+		NodeBlock = Block,
+	{
+		System: system::{},
+		Pallet1: pallet1::{} = 0,
+	}
+}
+
+fn main() {}
diff --git a/frame/support/test/tests/construct_runtime_ui/conflicting_index.stderr b/frame/support/test/tests/construct_runtime_ui/conflicting_index.stderr
new file mode 100644
index 0000000000000..65368666c88fe
--- /dev/null
+++ b/frame/support/test/tests/construct_runtime_ui/conflicting_index.stderr
@@ -0,0 +1,11 @@
+error: Module indices are conflicting: Both modules System and Pallet1 are at index 0
+ --> $DIR/conflicting_index.rs:9:3
+  |
+9 |         System: system::{},
+  |         ^^^^^^
+
+error: Module indices are conflicting: Both modules System and Pallet1 are at index 0
+  --> $DIR/conflicting_index.rs:10:3
+   |
+10 |         Pallet1: pallet1::{} = 0,
+   |         ^^^^^^^
diff --git a/frame/support/test/tests/construct_runtime_ui/conflicting_index_2.rs b/frame/support/test/tests/construct_runtime_ui/conflicting_index_2.rs
new file mode 100644
index 0000000000000..c949cb41a23fa
--- /dev/null
+++ b/frame/support/test/tests/construct_runtime_ui/conflicting_index_2.rs
@@ -0,0 +1,16 @@
+use frame_support::construct_runtime;
+
+construct_runtime! {
+	pub enum Runtime where
+		UncheckedExtrinsic = UncheckedExtrinsic,
+		Block = Block,
+		NodeBlock = Block,
+	{
+		System: system::{} = 5,
+		Pallet1: pallet1::{} = 3,
+		Pallet2: pallet2::{},
+		Pallet3: pallet3::{},
+	}
+}
+
+fn main() {}
diff --git a/frame/support/test/tests/construct_runtime_ui/conflicting_index_2.stderr b/frame/support/test/tests/construct_runtime_ui/conflicting_index_2.stderr
new file mode 100644
index 0000000000000..b792ff5d2a541
--- /dev/null
+++ b/frame/support/test/tests/construct_runtime_ui/conflicting_index_2.stderr
@@ -0,0 +1,11 @@
+error: Module indices are conflicting: Both modules System and Pallet3 are at index 5
+ --> $DIR/conflicting_index_2.rs:9:3
+  |
+9 |         System: system::{} = 5,
+  |         ^^^^^^
+
+error: Module indices are conflicting: Both modules System and Pallet3 are at index 5
+  --> $DIR/conflicting_index_2.rs:12:3
+   |
+12 |         Pallet3: pallet3::{},
+   |         ^^^^^^^
diff --git a/frame/support/test/tests/construct_runtime_ui/more_than_256_modules.rs b/frame/support/test/tests/construct_runtime_ui/more_than_256_modules.rs
new file mode 100644
index 0000000000000..4c8331ae442c8
--- /dev/null
+++ b/frame/support/test/tests/construct_runtime_ui/more_than_256_modules.rs
@@ -0,0 +1,14 @@
+use frame_support::construct_runtime;
+
+construct_runtime! {
+	pub enum Runtime where
+		UncheckedExtrinsic = UncheckedExtrinsic,
+		Block = Block,
+		NodeBlock = Block,
+	{
+		System: system::{} = 255,
+		Pallet256: pallet256::{},
+	}
+}
+
+fn main() {}
diff --git a/frame/support/test/tests/construct_runtime_ui/more_than_256_modules.stderr b/frame/support/test/tests/construct_runtime_ui/more_than_256_modules.stderr
new file mode 100644
index 0000000000000..c0ef5c8e60b9e
--- /dev/null
+++ b/frame/support/test/tests/construct_runtime_ui/more_than_256_modules.stderr
@@ -0,0 +1,5 @@
+error: Module index doesn't fit into u8, index is 256
+  --> $DIR/more_than_256_modules.rs:10:3
+   |
+10 |         Pallet256: pallet256::{},
+   |         ^^^^^^^^^
diff --git a/frame/support/test/tests/system.rs b/frame/support/test/tests/system.rs
index 90ce05199e16d..a7d4d43c341a9 100644
--- a/frame/support/test/tests/system.rs
+++ b/frame/support/test/tests/system.rs
@@ -31,7 +31,10 @@ pub trait Trait: 'static + Eq + Clone {
 }
 
 frame_support::decl_module! {
-	pub struct Module<T: Trait> for enum Call where origin: T::Origin, system=self {}
+	pub struct Module<T: Trait> for enum Call where origin: T::Origin, system=self {
+		#[weight = 0]
+		fn noop(origin) {}
+	}
 }
 
 impl<T: Trait> Module<T> {