diff --git a/ext/standard/string.c b/ext/standard/string.c
index 6f2c18ac2c5..0a5da0be408 100644
--- a/ext/standard/string.c
+++ b/ext/standard/string.c
@@ -4174,7 +4174,7 @@ static void php_strtr_array(zval *return_value, char *str, int slen, HashTable *
 }
 /* }}} */
 
-/* {{{ proto string strtr(string str, string from[, string to])
+/* {{{ proto string strtr(string str, string from[, string to]) U
    Translates characters in str using given translation tables */
 PHP_FUNCTION(strtr)
 {