diff --git a/lib/graphiti/resource/polymorphism.rb b/lib/graphiti/resource/polymorphism.rb
index b4ce54de..bc2bfd78 100644
--- a/lib/graphiti/resource/polymorphism.rb
+++ b/lib/graphiti/resource/polymorphism.rb
@@ -58,7 +58,7 @@ def children
         end
 
         def resource_for_type(type)
-          resource = children.find { |c| c.type == type }
+          resource = children.find { |c| c.type.to_s == type.to_s }
           if resource.nil?
             raise Errors::PolymorphicResourceChildNotFound.new(self, type: type)
           else
diff --git a/spec/request_validator_spec.rb b/spec/request_validator_spec.rb
index c59afcb8..39da77ab 100644
--- a/spec/request_validator_spec.rb
+++ b/spec/request_validator_spec.rb
@@ -175,6 +175,20 @@ def self.name
 
           expect(instance.errors).to be_blank
         end
+
+        context "when updating" do
+          before do
+            payload["action"] = "update"
+            payload[:data][:id] = 1
+            payload[:filter] = { id: 1 }
+          end
+
+          it "accepts the child type" do
+            validate
+
+            expect(instance.errors).to be_blank
+          end
+        end
       end
     end