diff --git a/jerry-core/ecma/operations/ecma-objects.c b/jerry-core/ecma/operations/ecma-objects.c
index 40f4b8e16..45e0f34ca 100644
--- a/jerry-core/ecma/operations/ecma-objects.c
+++ b/jerry-core/ecma/operations/ecma-objects.c
@@ -1682,6 +1682,9 @@ ecma_object_check_class_name_is_object (ecma_object_t *obj_p) /**< object */
 {
 #ifndef JERRY_NDEBUG
   return (ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_GLOBAL)
+#ifndef CONFIG_DISABLE_ES2015_PROMISE_BUILTIN
+          || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_PROMISE_PROTOTYPE)
+#endif /* !CONFIG_DISABLE_ES2015_PROMISE_BUILTIN */
 #ifndef CONFIG_DISABLE_ES2015_TYPEDARRAY_BUILTIN
           || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_ARRAYBUFFER_PROTOTYPE)
           || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_TYPEDARRAY_PROTOTYPE)
diff --git a/tests/jerry/es2015/regression-test-issue-1765.js b/tests/jerry/es2015/regression-test-issue-1765.js
new file mode 100644
index 000000000..d26b18721
--- /dev/null
+++ b/tests/jerry/es2015/regression-test-issue-1765.js
@@ -0,0 +1,15 @@
+// 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.
+
+Function()(Promise.prototype.toLocaleString())