diff --git a/ext/standard/tests/filters/user_filter_seek_01.phpt b/ext/standard/tests/filters/user_filter_seek_01.phpt
index cb4e9fe72267..31ec95ca6aa6 100644
--- a/ext/standard/tests/filters/user_filter_seek_01.phpt
+++ b/ext/standard/tests/filters/user_filter_seek_01.phpt
@@ -1,5 +1,7 @@
 --TEST--
 php_user_filter with seek method - always seekable (stateless filter)
+--EXTENSIONS--
+ctype
 --FILE--
 <?php