diff --git a/lib/octopus.rb b/lib/octopus.rb
index ffea3f78..95404e40 100644
--- a/lib/octopus.rb
+++ b/lib/octopus.rb
@@ -141,6 +141,7 @@ def self.using(shard, &block)
     conn = ActiveRecord::Base.connection
 
     if conn.is_a?(Octopus::Proxy)
+      conn.current_shard_dirty = true
       conn.run_queries_on_shard(shard, &block)
     else
       yield
diff --git a/lib/octopus/model.rb b/lib/octopus/model.rb
index ba9649e4..cc40e837 100644
--- a/lib/octopus/model.rb
+++ b/lib/octopus/model.rb
@@ -19,6 +19,7 @@ def using(shard)
         end
 
         if Octopus.enabled?
+          self.connection_proxy.current_shard_dirty = true
           Octopus::ScopeProxy.new(shard, self)
         else
           self
diff --git a/lib/octopus/proxy.rb b/lib/octopus/proxy.rb
index b18f5ab1..09e7c0d6 100644
--- a/lib/octopus/proxy.rb
+++ b/lib/octopus/proxy.rb
@@ -8,6 +8,7 @@ class Proxy
 
     delegate :current_model, :current_model=,
              :current_shard, :current_shard=,
+             :current_shard_dirty, :current_shard_dirty=,
              :current_group, :current_group=,
              :current_slave_group, :current_slave_group=,
              :current_load_balance_options, :current_load_balance_options=,
@@ -106,6 +107,7 @@ def send_queries_to_all_shards(&block)
 
     def clean_connection_proxy
       self.current_shard = Octopus.master_shard
+      self.current_shard_dirty = false
       self.current_model = nil
       self.current_group = nil
       self.block = nil
@@ -269,7 +271,7 @@ def should_clean_connection_proxy?(method)
 
     # Try to use slaves if and only if `replicated: true` is specified in `shards.yml` and no slaves groups are defined
     def should_send_queries_to_replicated_databases?(method)
-      replicated && method.to_s =~ /select/ && !block && !slaves_grouped?
+      replicated && method.to_s =~ /select/ && (!block || !current_shard_dirty) && !slaves_grouped?
     end
 
     def send_queries_to_selected_slave(method, *args, &block)
@@ -335,6 +337,7 @@ def keeping_connection_proxy(shard, &_block)
     # Temporarily switch `current_shard` and run the block
     def using_shard(shard, &_block)
       older_shard = current_shard
+      older_dirty = current_shard_dirty
       older_slave_group = current_slave_group
       older_load_balance_options = current_load_balance_options
 
@@ -345,6 +348,7 @@ def using_shard(shard, &_block)
         yield
       ensure
         self.current_shard = older_shard
+        self.current_shard_dirty = older_dirty
         self.current_slave_group = older_slave_group
         self.current_load_balance_options = older_load_balance_options
       end
diff --git a/lib/octopus/proxy_config.rb b/lib/octopus/proxy_config.rb
index 93a2e5bc..688970f7 100644
--- a/lib/octopus/proxy_config.rb
+++ b/lib/octopus/proxy_config.rb
@@ -2,6 +2,7 @@ module Octopus
   class ProxyConfig
     CURRENT_MODEL_KEY = 'octopus.current_model'.freeze
     CURRENT_SHARD_KEY = 'octopus.current_shard'.freeze
+    CURRENT_SHARD_DIRTY_KEY = 'octopus.current_shard_dirty'.freeze
     CURRENT_GROUP_KEY = 'octopus.current_group'.freeze
     CURRENT_SLAVE_GROUP_KEY = 'octopus.current_slave_group'.freeze
     CURRENT_LOAD_BALANCE_OPTIONS_KEY = 'octopus.current_load_balance_options'.freeze
@@ -25,6 +26,14 @@ def current_model=(model)
       Thread.current[CURRENT_MODEL_KEY] = model.is_a?(ActiveRecord::Base) ? model.class : model
     end
 
+    def current_shard_dirty
+      Thread.current[CURRENT_SHARD_DIRTY_KEY] ||= false
+    end
+
+    def current_shard_dirty=(value)
+      Thread.current[CURRENT_SHARD_DIRTY_KEY] = value
+    end
+
     def current_shard
       Thread.current[CURRENT_SHARD_KEY] ||= Octopus.master_shard
     end
diff --git a/lib/octopus/scope_proxy.rb b/lib/octopus/scope_proxy.rb
index 0cf3dd5b..5e50ef67 100644
--- a/lib/octopus/scope_proxy.rb
+++ b/lib/octopus/scope_proxy.rb
@@ -23,6 +23,7 @@ def initialize(shard, klass)
     def using(shard)
       fail "Nonexistent Shard Name: #{shard}" if @klass.connection.shards[shard].nil?
       @current_shard = shard
+      @klass.connection_proxy.current_shard_dirty = true
       self
     end
 
diff --git a/spec/octopus/octopus_spec.rb b/spec/octopus/octopus_spec.rb
index db2077bf..09a408e3 100644
--- a/spec/octopus/octopus_spec.rb
+++ b/spec/octopus/octopus_spec.rb
@@ -88,34 +88,86 @@
   end
 
   describe '#fully_replicated' do
-    before do
-      OctopusHelper.using_environment :production_replicated do
-        OctopusHelper.clean_all_shards([:slave1, :slave2, :slave3, :slave4])
-        4.times { |i| User.using(:"slave#{i + 1}").create!(:name => 'Slave User') }
+    describe '#without_association' do
+      before do
+        OctopusHelper.using_environment :production_replicated do
+          OctopusHelper.clean_all_shards([:slave1, :slave2, :slave3, :slave4])
+          4.times { |i| User.using(:"slave#{i + 1}").create!(:name => 'Slave User') }
+        end
+      end
+
+      it 'sends queries to slaves' do
+        OctopusHelper.using_environment :production_replicated do
+          expect(User.count).to eq(0)
+          4.times do |_i|
+            Octopus.fully_replicated do
+              expect(User.count).to eq(1)
+            end
+          end
+        end
       end
-    end
 
-    it 'sends queries to slaves' do
-      OctopusHelper.using_environment :production_replicated do
-        expect(User.count).to eq(0)
-        4.times do |_i|
+      it 'sends queries to master when forced to use master' do
+        OctopusHelper.using_environment :production_replicated do
           Octopus.fully_replicated do
+            expect(User.using(:master).count).to eq(0)
+          end
+        end
+      end
+
+      it 'allows nesting' do
+        OctopusHelper.using_environment :production_replicated do
+          Octopus.fully_replicated do
+            expect(User.count).to eq(1)
+
+            Octopus.fully_replicated do
+              expect(User.count).to eq(1)
+            end
+
             expect(User.count).to eq(1)
           end
         end
       end
     end
 
-    it 'allows nesting' do
-      OctopusHelper.using_environment :production_replicated do
-        Octopus.fully_replicated do
-          expect(User.count).to eq(1)
+    describe '#with_association' do
+      before do
+        OctopusHelper.using_environment :production_replicated do
+          master = Client.create!(:name => 'Master Client')
+          OctopusHelper.clean_all_shards([:slave1, :slave2, :slave3, :slave4])
+          Octopus.fully_replicated do
+            4.times do |i|
+              client = Client.using(:"slave#{i + 1}").create!(master.as_json)
+              client.items << Item.using(:"slave#{i + 1}").create(:name => 'Slave Item')
+              client.save
+            end
+          end
+        end
+      end
+
+      it 'sends queries to slaves' do
+        OctopusHelper.using_environment :production_replicated do
+          4.times do |_i|
+            Octopus.fully_replicated do
+              expect(Client.last.items.count).to eq(1)
+            end
+          end
+        end
+      end
 
+      it 'sends queries to master when forced to use master' do
+        OctopusHelper.using_environment :production_replicated do
           Octopus.fully_replicated do
-            expect(User.count).to eq(1)
+            expect(Client.using(:master).last.items.count).to eq(0)
           end
+        end
+      end
 
-          expect(User.count).to eq(1)
+      it 'sends queries to slave when forced to use slave' do
+        OctopusHelper.using_environment :production_replicated do
+          Octopus.fully_replicated do
+            expect(Client.using(:slave1).last.items.count).to eq(1)
+          end
         end
       end
     end
diff --git a/spec/support/octopus_helper.rb b/spec/support/octopus_helper.rb
index 01db6431..f501dc8d 100644
--- a/spec/support/octopus_helper.rb
+++ b/spec/support/octopus_helper.rb
@@ -20,6 +20,7 @@ def self.clean_all_shards(shards)
   def self.clean_connection_proxy
     Thread.current['octopus.current_model'] = nil
     Thread.current['octopus.current_shard'] = nil
+    Thread.current['octopus.current_shard_dirty'] = false
     Thread.current['octopus.current_group'] = nil
     Thread.current['octopus.current_slave_group'] = nil
     Thread.current['octopus.block'] = nil