diff --git a/ext/standard/string.c b/ext/standard/string.c
index 53b6a9063a0..d6494c5536a 100644
--- a/ext/standard/string.c
+++ b/ext/standard/string.c
@@ -425,6 +425,7 @@ PHPAPI char *php_strtolower(char *s, size_t len)
 {
 	register int ch;
 	char *c;
+	int i;
 
 	c = s;
 	for (i=0; i<len; i++) {
@@ -2161,7 +2162,7 @@ PHPAPI void php_strip_tags(char *rbuf, int len, int state, char *allow) {
 	rp = rbuf;
 	br = 0;
 	if(allow) {
-		php_strtolower(allow);
+		php_strtolower(allow, len);
 		tbuf = emalloc(PHP_TAG_BUF_SIZE+1);
 		tp = tbuf;
 	} else {