diff --git a/system/helpers/string_helper.php b/system/helpers/string_helper.php
index 28e6ab1..6378351 100644
--- a/system/helpers/string_helper.php
+++ b/system/helpers/string_helper.php
@@ -253,7 +253,7 @@
 	 */
 	function increment_string($str, $separator = '_', $first = 1)
 	{
-		preg_match('/(.+)' . preg_quote($separator) . '([0-9]+)$/', $str, $match);
+		preg_match('/(.+)'.preg_quote($separator, '/').'([0-9]+)$/', $str, $match);
 		return isset($match[2]) ? $match[1].$separator.($match[2] + 1) : $str.$separator.$first;
 	}
 }