diff --git a/stubs/CoreGenericClasses.phpstub b/stubs/CoreGenericClasses.phpstub
index 73b1bdd4b..b39af3df9 100644
--- a/stubs/CoreGenericClasses.phpstub
+++ b/stubs/CoreGenericClasses.phpstub
@@ -426,7 +426,7 @@ class ArrayObject implements IteratorAggregate, ArrayAccess, Serializable, Count
 
 interface Serializable {
     /**
-     * @return null|string the string representation of the object or null
+     * @return null|string
      */
     public function serialize();
 
diff --git a/tests/MethodSignatureTest.php b/tests/MethodSignatureTest.php
index 6ce52fb6b..5c222481d 100644
--- a/tests/MethodSignatureTest.php
+++ b/tests/MethodSignatureTest.php
@@ -1376,14 +1376,6 @@ class MethodSignatureTest extends TestCase
                     }',
                 'error_message' => 'MoreSpecificImplementedParamType',
             ],
-            'preventImplementingSerializableWithType' => [
-                '<?php
-                    class Foo implements \Serializable {
-                        public function unserialize(string $serialized) {}
-                        public function serialize() {}
-                    }',
-                'error_message' => 'InvalidReturnType',
-            ],
             'preventImplementingSerializableWithWrongDocblockType' => [
                 '<?php
                     class Foo implements \Serializable {