diff --git a/src/coreclr/tools/Common/TypeSystem/Interop/IL/Marshaller.cs b/src/coreclr/tools/Common/TypeSystem/Interop/IL/Marshaller.cs
index f78e4df8a29e7f..404f6559512fee 100644
--- a/src/coreclr/tools/Common/TypeSystem/Interop/IL/Marshaller.cs
+++ b/src/coreclr/tools/Common/TypeSystem/Interop/IL/Marshaller.cs
@@ -1483,8 +1483,12 @@ internal override bool CleanupRequired
 
         internal override void EmitElementCleanup(ILCodeStream codeStream, ILEmitter emitter)
         {
+#if READYTORUN
+            throw new NotSupportedException();
+#else
             codeStream.Emit(ILOpcode.call, emitter.NewToken(
                                 Context.GetHelperEntryPoint("InteropHelpers", "CoTaskMemFree")));
+#endif
         }
 
         protected override void TransformManagedToNative(ILCodeStream codeStream)
@@ -1536,12 +1540,16 @@ protected override void TransformManagedToNative(ILCodeStream codeStream)
             }
             else
             {
+#if READYTORUN
+                throw new NotSupportedException();
+#else
                 var helper = Context.GetHelperEntryPoint("InteropHelpers", "StringToUnicodeBuffer");
                 LoadManagedValue(codeStream);
 
                 codeStream.Emit(ILOpcode.call, emitter.NewToken(helper));
 
                 StoreNativeValue(codeStream);
+#endif
             }
         }
 
@@ -1597,8 +1605,12 @@ internal override bool CleanupRequired
 
         internal override void EmitElementCleanup(ILCodeStream codeStream, ILEmitter emitter)
         {
+#if READYTORUN
+            throw new NotSupportedException();
+#else
             codeStream.Emit(ILOpcode.call, emitter.NewToken(
                                 Context.GetHelperEntryPoint("InteropHelpers", "CoTaskMemFree")));
+#endif
         }
 
         protected override void TransformManagedToNative(ILCodeStream codeStream)
@@ -1752,6 +1764,7 @@ protected override void EmitCleanupManaged(ILCodeStream codeStream)
         }
     }
 
+#if !READYTORUN
     class UTF8StringMarshaller : Marshaller
     {
         internal override bool CleanupRequired
@@ -1806,6 +1819,7 @@ protected override void EmitCleanupManaged(ILCodeStream codeStream)
             codeStream.EmitLabel(lNullCheck);
         }
     }
+#endif
 
     class SafeHandleMarshaller : Marshaller
     {
diff --git a/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Interop/IL/Marshaller.ReadyToRun.cs b/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Interop/IL/Marshaller.ReadyToRun.cs
index 636c698e8d5899..7da42e09791fda 100644
--- a/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Interop/IL/Marshaller.ReadyToRun.cs
+++ b/src/coreclr/tools/aot/ILCompiler.ReadyToRun/Interop/IL/Marshaller.ReadyToRun.cs
@@ -25,8 +25,6 @@ protected static Marshaller CreateMarshaller(MarshallerKind kind)
                     return new BooleanMarshaller();
                 case MarshallerKind.AnsiString:
                     return new AnsiStringMarshaller();
-                case MarshallerKind.UTF8String:
-                    return new UTF8StringMarshaller();
                 case MarshallerKind.SafeHandle:
                     return new SafeHandleMarshaller();
                 case MarshallerKind.UnicodeString: