diff --git a/tensorflow/lite/mutable_op_resolver_test.cc b/tensorflow/lite/mutable_op_resolver_test.cc
index 64fc68a16ca..22641ebd539 100644
--- a/tensorflow/lite/mutable_op_resolver_test.cc
+++ b/tensorflow/lite/mutable_op_resolver_test.cc
@@ -40,11 +40,21 @@ TfLiteStatus Dummy2Invoke(TfLiteContext* context, TfLiteNode* node) {
   return kTfLiteOk;
 }
 
+TfLiteStatus Dummy2Prepare(TfLiteContext* context, TfLiteNode* node) {
+  return kTfLiteOk;
+}
+
+void* Dummy2Init(TfLiteContext* context, const char* buffer, size_t length) {
+  return nullptr;
+}
+
+void Dummy2free(TfLiteContext* context, void* buffer) {}
+
 TfLiteRegistration* GetDummy2Registration() {
   static TfLiteRegistration registration = {
-      .init = nullptr,
-      .free = nullptr,
-      .prepare = nullptr,
+      .init = Dummy2Init,
+      .free = Dummy2free,
+      .prepare = Dummy2Prepare,
       .invoke = Dummy2Invoke,
   };
   return &registration;
@@ -112,8 +122,41 @@ TEST(MutableOpResolverTest, FindCustomOp) {
   EXPECT_EQ(found_registration->builtin_code, BuiltinOperator_CUSTOM);
   EXPECT_TRUE(found_registration->invoke == DummyInvoke);
   EXPECT_EQ(found_registration->version, 1);
-  // TODO(ycling): The `custom_name` in TfLiteRegistration isn't properly
-  // filled yet. Fix this and add tests.
+}
+
+TEST(MutableOpResolverTest, FindCustomName) {
+  MutableOpResolver resolver;
+  TfLiteRegistration* reg = GetDummyRegistration();
+
+  reg->custom_name = "UPDATED";
+  resolver.AddCustom(reg->custom_name, reg);
+  const TfLiteRegistration* found_registration =
+      resolver.FindOp(reg->custom_name, 1);
+
+  ASSERT_NE(found_registration, nullptr);
+  EXPECT_EQ(found_registration->builtin_code, BuiltinOperator_CUSTOM);
+  EXPECT_EQ(found_registration->invoke, GetDummyRegistration()->invoke);
+  EXPECT_EQ(found_registration->version, 1);
+  EXPECT_EQ(found_registration->custom_name, "UPDATED");
+}
+
+TEST(MutableOpResolverTest, FindBuiltinName) {
+  MutableOpResolver resolver1;
+  TfLiteRegistration* reg = GetDummy2Registration();
+
+  reg->custom_name = "UPDATED";
+  resolver1.AddBuiltin(BuiltinOperator_ADD, reg);
+
+  ASSERT_EQ(resolver1.FindOp(BuiltinOperator_ADD, 1)->invoke,
+            GetDummy2Registration()->invoke);
+  ASSERT_EQ(resolver1.FindOp(BuiltinOperator_ADD, 1)->prepare,
+            GetDummy2Registration()->prepare);
+  ASSERT_EQ(resolver1.FindOp(BuiltinOperator_ADD, 1)->init,
+            GetDummy2Registration()->init);
+  ASSERT_EQ(resolver1.FindOp(BuiltinOperator_ADD, 1)->free,
+            GetDummy2Registration()->free);
+  // custom_name for builtin ops will be nullptr
+  EXPECT_EQ(resolver1.FindOp(BuiltinOperator_ADD, 1)->custom_name, nullptr);
 }
 
 TEST(MutableOpResolverTest, FindMissingCustomOp) {