diff --git a/jerry-core/ecma/operations/ecma-objects.c b/jerry-core/ecma/operations/ecma-objects.c
index 043fdccd4..857badb59 100644
--- a/jerry-core/ecma/operations/ecma-objects.c
+++ b/jerry-core/ecma/operations/ecma-objects.c
@@ -2357,6 +2357,12 @@ ecma_object_check_class_name_is_object (ecma_object_t *obj_p) /**< object */
           || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_SET_ITERATOR_PROTOTYPE)
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_ITERATOR) */
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_SET) */
+#if ENABLED (JERRY_ES2015_BUILTIN_WEAKMAP)
+          || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_WEAKMAP_PROTOTYPE)
+#endif /* ENABLED (JERRY_ES2015_BUILTIN_WEAKMAP) */
+#if ENABLED (JERRY_ES2015_BUILTIN_WEAKSET)
+          || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_WEAKSET_PROTOTYPE)
+#endif /* ENABLED (JERRY_ES2015_BUILTIN_WEAKSET) */
 #if ENABLED (JERRY_ES2015)
           || ecma_builtin_is (obj_p, ECMA_BUILTIN_ID_SYMBOL_PROTOTYPE)
 #endif /* ENABLED (JERRY_ES2015) */
diff --git a/tests/jerry/es2015/weakmap.js b/tests/jerry/es2015/weakmap.js
index c4ecd73c3..ff4e7286a 100644
--- a/tests/jerry/es2015/weakmap.js
+++ b/tests/jerry/es2015/weakmap.js
@@ -135,6 +135,8 @@ try {
   assert (e instanceof TypeError);
 }
 
+assert (WeakMap.prototype.toString() === "[object WeakMap]");
+
 WeakMap.prototype.set = function () { throw "abrupt set" };
 
 try {
diff --git a/tests/jerry/es2015/weakset.js b/tests/jerry/es2015/weakset.js
index f01a8634b..adb9bacab 100644
--- a/tests/jerry/es2015/weakset.js
+++ b/tests/jerry/es2015/weakset.js
@@ -119,6 +119,8 @@ try {
   assert (e instanceof TypeError);
 }
 
+assert (WeakSet.prototype.toString() === "[object WeakSet]");
+
 WeakSet.prototype.add = function () { throw "abrupt add" };
 
 try {