diff --git a/phpBB/includes/search/fulltext_native.php b/phpBB/includes/search/fulltext_native.php
index 5cc7fd31c7..b47076228a 100755
--- a/phpBB/includes/search/fulltext_native.php
+++ b/phpBB/includes/search/fulltext_native.php
@@ -91,7 +91,7 @@ class fulltext_native extends search_backend
 		}
 
 		$open_bracket = $space = false;
-		for ($i = 0, $n = $keywords; $i < $n; $i++)
+		for ($i = 0, $n = strlen($keywords); $i < $n; $i++)
 		{
 			if ($open_bracket !== false)
 			{