diff --git a/jerry-core/ecma/builtin-objects/ecma-builtin-map-prototype.inc.h b/jerry-core/ecma/builtin-objects/ecma-builtin-map-prototype.inc.h
index 68e56e6b59..a8c25e1419 100644
--- a/jerry-core/ecma/builtin-objects/ecma-builtin-map-prototype.inc.h
+++ b/jerry-core/ecma/builtin-objects/ecma-builtin-map-prototype.inc.h
@@ -54,7 +54,7 @@ ROUTINE (LIT_GLOBAL_SYMBOL_ITERATOR, ecma_builtin_map_prototype_object_entries,
 /* ECMA-262 v6, 23.1.3.10 */
 ACCESSOR_READ_ONLY (LIT_MAGIC_STRING_SIZE,
                     ecma_builtin_map_prototype_object_size_getter,
-                    ECMA_PROPERTY_FIXED)
+                    ECMA_PROPERTY_FLAG_CONFIGURABLE)
 
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_MAP) */
 
diff --git a/jerry-core/ecma/builtin-objects/ecma-builtin-set-prototype.inc.h b/jerry-core/ecma/builtin-objects/ecma-builtin-set-prototype.inc.h
index baafe95b2a..9e070503e2 100644
--- a/jerry-core/ecma/builtin-objects/ecma-builtin-set-prototype.inc.h
+++ b/jerry-core/ecma/builtin-objects/ecma-builtin-set-prototype.inc.h
@@ -52,7 +52,7 @@ ROUTINE (LIT_GLOBAL_SYMBOL_ITERATOR, ecma_builtin_set_prototype_object_values, 0
 
 ACCESSOR_READ_ONLY (LIT_MAGIC_STRING_SIZE,
                     ecma_builtin_set_prototype_object_size_getter,
-                    ECMA_PROPERTY_FIXED)
+                    ECMA_PROPERTY_FLAG_CONFIGURABLE)
 
 #endif /* ENABLED (JERRY_ES2015_BUILTIN_SET) */
 
diff --git a/tests/test262-es6-excludelist.xml b/tests/test262-es6-excludelist.xml
index 26482f647e..d8d5dfa907 100644
--- a/tests/test262-es6-excludelist.xml
+++ b/tests/test262-es6-excludelist.xml
@@ -45,7 +45,6 @@
   <test id="built-ins/GeneratorFunction/instance-restricted-properties.js"><reason></reason></test>
   <test id="built-ins/GeneratorPrototype/next/context-constructor-invocation.js"><reason></reason></test>
   <test id="built-ins/GeneratorPrototype/throw/from-state-completed.js"><reason></reason></test>
-  <test id="built-ins/Map/prototype/size/size.js"><reason></reason></test>
   <test id="built-ins/Map/prototype/Symbol.iterator.js"><reason></reason></test>
   <test id="built-ins/Number/15.7.4-1.js"><reason></reason></test>
   <test id="built-ins/Number/prototype/S15.7.3.1_A2_T1.js"><reason></reason></test>
@@ -146,7 +145,6 @@
   <test id="built-ins/RegExp/prototype/Symbol.search/get-sticky-err.js"><reason></reason></test>
   <test id="built-ins/RegExp/prototype/test/get-sticky-err.js"><reason></reason></test>
   <test id="built-ins/Set/prototype/keys/keys.js"><reason></reason></test>
-  <test id="built-ins/Set/prototype/size/size.js"><reason></reason></test>
   <test id="built-ins/Set/prototype/Symbol.iterator.js"><reason></reason></test>
   <test id="built-ins/String/prototype/normalize/form-is-not-valid-throws.js"><reason></reason></test>
   <test id="built-ins/String/prototype/normalize/length.js"><reason></reason></test>