diff --git a/ext/mbstring/tests/gh20836_stack_limit.phpt b/ext/mbstring/tests/gh20836_stack_limit.phpt
index b58833ff80cf..29d7f3f168cf 100644
--- a/ext/mbstring/tests/gh20836_stack_limit.phpt
+++ b/ext/mbstring/tests/gh20836_stack_limit.phpt
@@ -12,7 +12,7 @@ if (getenv('SKIP_ASAN')) {
 }
 ?>
 --INI--
-zend.max_allowed_stack_size=128K
+zend.max_allowed_stack_size=256K
 --FILE--
 <?php