diff --git a/lib/mongoid/extensions/hash.rb b/lib/mongoid/extensions/hash.rb
index 086473c2a7..4a187807b8 100644
--- a/lib/mongoid/extensions/hash.rb
+++ b/lib/mongoid/extensions/hash.rb
@@ -43,7 +43,7 @@ def __consolidate__(klass)
               real_key = klass.database_field_name(key2)
 
               value.delete(key2) if real_key != key2
-              value[real_key] = (key == "$rename") ? value2.to_s : mongoize_for(key, klass, real_key, value2)
+              value[real_key] = value_for(key, klass, real_key, value2)
             end
             consolidated[key] ||= {}
             consolidated[key].update(value)
@@ -185,6 +185,24 @@ def to_criteria
 
       private
 
+      # Get the value for the provided operator, klass, key and value.
+      #
+      # This is necessary for special cases like $rename, $addToSet and $push.
+      #
+      # @param [ String ] operator The operator.
+      # @param [ Class ] klass The model class.
+      # @param [ String | Symbol ] key The field key.
+      # @param [ Object ] value The original value.
+      #
+      # @return [ Object ] Value prepared for the provided operator.
+      def value_for(operator, klass, key, value)
+        case operator
+        when "$rename" then value.to_s
+        when "$addToSet", "$push" then value.mongoize
+        else mongoize_for(operator, klass, operator, value)
+        end
+      end
+
       # Mongoize for the klass, key and value.
       #
       # @api private
diff --git a/spec/mongoid/contextual/mongo_spec.rb b/spec/mongoid/contextual/mongo_spec.rb
index 159a912b3d..c10a8aa939 100644
--- a/spec/mongoid/contextual/mongo_spec.rb
+++ b/spec/mongoid/contextual/mongo_spec.rb
@@ -3700,16 +3700,51 @@
 
         context "when the attributes are in the correct type" do
 
-          before do
-            context.update_all("$set" => { name: "Smiths" })
+          context "when operation is $set" do
+
+            before do
+              context.update_all("$set" => { name: "Smiths" })
+            end
+
+            it "updates the first matching document" do
+              expect(depeche_mode.reload.name).to eq("Smiths")
+            end
+
+            it "updates the last matching document" do
+              expect(new_order.reload.name).to eq("Smiths")
+            end
           end
 
-          it "updates the first matching document" do
-            expect(depeche_mode.reload.name).to eq("Smiths")
+          context "when operation is $push" do
+
+            before do
+              depeche_mode.update_attribute(:genres, ["electronic"])
+              new_order.update_attribute(:genres, ["electronic"])
+              context.update_all("$push" => { genres: "pop" })
+            end
+
+            it "updates the first matching document" do
+              expect(depeche_mode.reload.genres).to eq(["electronic", "pop"])
+            end
+
+            it "updates the last matching document" do
+              expect(new_order.reload.genres).to eq(["electronic", "pop"])
+            end
           end
 
-          it "updates the last matching document" do
-            expect(new_order.reload.name).to eq("Smiths")
+          context "when operation is $addToSet" do
+
+            before do
+              context.update_all("$addToSet" => { genres: "electronic" })
+            end
+
+            it "updates the first matching document" do
+              expect(depeche_mode.reload.genres).to eq(["electronic"])
+            end
+
+            it "updates the last matching document" do
+              expect(new_order.reload.genres).to eq(["electronic"])
+            end
           end
         end