diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5033e6192f..5c5a4db0f1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,9 @@ For instructions on upgrading to newer versions, visit
 
 ### Resolved Issues
 
+* \#1640 Update consumers should be tied to the name of the collection
+  they persist to, not the name of the class.
+
 * \#1636 Scopes no longer modify parent class scopes when subclassing.
   (Hans Hasselberg)
 
diff --git a/lib/mongoid/collection.rb b/lib/mongoid/collection.rb
index de33bbe9e4..ecbb8bf8fa 100644
--- a/lib/mongoid/collection.rb
+++ b/lib/mongoid/collection.rb
@@ -142,7 +142,7 @@ def master(options = {})
     #
     # @since 2.0.0
     def update(selector, document, options = {})
-      updater = Threaded.update_consumer(klass)
+      updater = Threaded.update_consumer(name)
       if updater
         updater.consume(selector, document, options)
       else
diff --git a/lib/mongoid/contexts/enumerable.rb b/lib/mongoid/contexts/enumerable.rb
index 2ec03187d9..a6bae2f59b 100644
--- a/lib/mongoid/contexts/enumerable.rb
+++ b/lib/mongoid/contexts/enumerable.rb
@@ -210,6 +210,18 @@ def update_all(attributes = nil)
 
       protected
 
+      # Get the root class collection name.
+      #
+      # @example Get the root class collection name.
+      #   context.collection_name
+      #
+      # @return [ String ] The name of the collection.
+      #
+      # @since 2.4.3
+      def collection_name
+        root ? root.collection_name : nil
+      end
+
       # Filters the documents against the criteria's selector
       #
       # @example Filter the documents.
@@ -251,10 +263,22 @@ def limit(documents)
         documents
       end
 
+      # Get the root document for the enumerable.
+      #
+      # @example Get the root document.
+      #   context.root
+      #
+      # @return [ Document ] The root.
       def root
         @root ||= documents.first.try(:_root)
       end
 
+      # Get the root class for the enumerable.
+      #
+      # @example Get the root class.
+      #   context.root_class
+      #
+      # @return [ Class ] The root class.
       def root_class
         @root_class ||= root ? root.class : nil
       end
diff --git a/lib/mongoid/relations/embedded/atomic.rb b/lib/mongoid/relations/embedded/atomic.rb
index 2e96c301e7..53262c1757 100644
--- a/lib/mongoid/relations/embedded/atomic.rb
+++ b/lib/mongoid/relations/embedded/atomic.rb
@@ -55,13 +55,13 @@ module Atomic
         #
         # @since 2.0.0
         def atomically(modifier, &block)
-          updater = Threaded.update_consumer(root_class) ||
-            Threaded.set_update_consumer(root_class, MODIFIERS[modifier].new)
+          updater = Threaded.update_consumer(collection_name) ||
+            Threaded.set_update_consumer(collection_name, MODIFIERS[modifier].new)
           count_executions do
             block.call if block
           end.tap do
             if @executions.zero?
-              Threaded.set_update_consumer(root_class, nil)
+              Threaded.set_update_consumer(collection_name, nil)
               updater.execute(collection)
             end
           end
diff --git a/lib/mongoid/relations/proxy.rb b/lib/mongoid/relations/proxy.rb
index d77ad5aff8..4aeab48d23 100644
--- a/lib/mongoid/relations/proxy.rb
+++ b/lib/mongoid/relations/proxy.rb
@@ -18,6 +18,7 @@ class Proxy
       # Backwards compatibility with Mongoid beta releases.
       delegate :klass, :to => :metadata
       delegate :bind_one, :unbind_one, :to => :binding
+      delegate :collection_name, :to => :base
 
       # Convenience for setting the target and the metadata properties since
       # all proxies will need to do this.
diff --git a/spec/functional/mongoid/relations/embedded/many_spec.rb b/spec/functional/mongoid/relations/embedded/many_spec.rb
index 0d88513919..a34ac070c0 100644
--- a/spec/functional/mongoid/relations/embedded/many_spec.rb
+++ b/spec/functional/mongoid/relations/embedded/many_spec.rb
@@ -317,6 +317,60 @@
       end
     end
 
+    context "when setting for inherited docs" do
+
+      context "when the parent collection is already accessed" do
+
+        before do
+          Person.collection
+        end
+
+        context "when setting via the subclass" do
+
+          let(:doctor) do
+            Doctor.new
+          end
+
+          let(:address_one) do
+            Address.new(:street => "tauentzien")
+          end
+
+          before do
+            doctor.addresses = [ address_one ]
+            doctor.save
+          end
+
+          it "sets the documents" do
+            doctor.addresses.should eq([ address_one ])
+          end
+
+          it "persists the document" do
+            doctor.reload.addresses.should eq([ address_one ])
+          end
+
+          context "when setting the relation multiple times" do
+
+            let(:address_two) do
+              Address.new(:street => "kudamm")
+            end
+
+            before do
+              doctor.addresses = [ address_two ]
+              doctor.save
+            end
+
+            it "sets the new documents" do
+              doctor.addresses.should eq([ address_two ])
+            end
+
+            it "persits only the new documents" do
+              doctor.reload.addresses.should eq([ address_two ])
+            end
+          end
+        end
+      end
+    end
+
     context "when replacing an existing relation" do
 
       let(:person) do
diff --git a/spec/unit/mongoid/relations/embedded/atomic_spec.rb b/spec/unit/mongoid/relations/embedded/atomic_spec.rb
index 7918570db8..def27f2e6a 100644
--- a/spec/unit/mongoid/relations/embedded/atomic_spec.rb
+++ b/spec/unit/mongoid/relations/embedded/atomic_spec.rb
@@ -12,6 +12,10 @@ def collection
     def root_class
       Person
     end
+
+    def collection_name
+      "people"
+    end
   end
 
   describe "#atomically" do
@@ -35,7 +39,7 @@ def root_class
 
         it "puts the updater on the current thread" do
           klass.send(:atomically, :$set) do
-            Mongoid::Threaded.update_consumer(Person).should eq(set)
+            Mongoid::Threaded.update_consumer("people").should eq(set)
           end
         end
       end
@@ -44,7 +48,7 @@ def root_class
 
         it "removes the updater from the current thread" do
           klass.send(:atomically, :$set)
-          Mongoid::Threaded.update_consumer(Person).should be_nil
+          Mongoid::Threaded.update_consumer("people").should be_nil
         end
       end
     end