diff --git a/jerry-core/ecma/operations/ecma-objects.c b/jerry-core/ecma/operations/ecma-objects.c
index 9aa2813f8..448efd5b7 100644
--- a/jerry-core/ecma/operations/ecma-objects.c
+++ b/jerry-core/ecma/operations/ecma-objects.c
@@ -2569,6 +2569,7 @@ ecma_object_check_class_name_is_object (ecma_object_t *obj_p) /**< object */
           || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_DATE_PROTOTYPE)
           || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_REGEXP_PROTOTYPE)
           || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_SYMBOL_PROTOTYPE)
+          || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_ASYNC_FUNCTION_PROTOTYPE)
 #endif /* ENABLED (JERRY_ESNEXT) */
 #if ENABLED (JERRY_BUILTIN_MAP)
           || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_MAP_PROTOTYPE)
diff --git a/tests/jerry/es.next/regression-test-issue-4147.js b/tests/jerry/es.next/regression-test-issue-4147.js
new file mode 100644
index 000000000..349e0243c
--- /dev/null
+++ b/tests/jerry/es.next/regression-test-issue-4147.js
@@ -0,0 +1,16 @@
+// Copyright JS Foundation and other contributors, http://js.foundation
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+var asyncFunProto = Object.getPrototypeOf (async function() {});
+assert (Object.prototype.toString.call (asyncFunProto) === "[object AsyncFunction]")