diff --git a/lib/mongoid/fields.rb b/lib/mongoid/fields.rb
index 69b0a5cb86..37d91d6bef 100644
--- a/lib/mongoid/fields.rb
+++ b/lib/mongoid/fields.rb
@@ -21,7 +21,6 @@ module Fields
       self.pre_processed_defaults = []
       self.post_processed_defaults = []
 
-      field(:_type, default: ->{ self.class.name if hereditary? }, type: String)
       field(
         :_id,
         default: ->{ Moped::BSON::ObjectId.new },
diff --git a/lib/mongoid/hierarchy.rb b/lib/mongoid/hierarchy.rb
index 8d80d52157..1c8315b2e6 100644
--- a/lib/mongoid/hierarchy.rb
+++ b/lib/mongoid/hierarchy.rb
@@ -145,6 +145,13 @@ def inherited(subclass)
         subclass.pre_processed_defaults = pre_processed_defaults.dup
         subclass.post_processed_defaults = post_processed_defaults.dup
         subclass.scopes = scopes.dup
+
+        # We only need the _type field if inheritance is in play, but need to
+        # add to the root class as well for backwards compatibility.
+        unless fields.has_key?("_type")
+          field(:_type, default: self.name, type: String)
+        end
+        subclass.field(:_type, default: subclass.name, type: String)
       end
     end
   end
diff --git a/spec/mongoid/fields_spec.rb b/spec/mongoid/fields_spec.rb
index da4d9039a8..78780cb23a 100644
--- a/spec/mongoid/fields_spec.rb
+++ b/spec/mongoid/fields_spec.rb
@@ -634,7 +634,7 @@
       end
 
       it "does not return subclass defaults" do
-        shape.pre_processed_defaults.should eq([ "_id", "x", "y" ])
+        shape.pre_processed_defaults.should eq([ "_id", "x", "y", "_type" ])
       end
     end
 
@@ -645,7 +645,7 @@
       end
 
       it "has the parent and child defaults" do
-        circle.pre_processed_defaults.should eq([ "_id", "x", "y", "radius" ])
+        circle.pre_processed_defaults.should eq([ "_id", "x", "y", "_type", "radius" ])
       end
     end
   end