diff --git a/system/helpers/inflector_helper.php b/system/helpers/inflector_helper.php
index 96b723c..c064d8d 100644
--- a/system/helpers/inflector_helper.php
+++ b/system/helpers/inflector_helper.php
@@ -219,7 +219,7 @@
 	 */
 	function humanize($str, $separator = '_')
 	{
-		return ucwords(preg_replace('/['.$separator.']+/', ' ', trim(MB_ENABLED ? mb_strtolower($str) : strtolower($str))));
+		return ucwords(preg_replace('/['.preg_quote($separator).']+/', ' ', trim(MB_ENABLED ? mb_strtolower($str) : strtolower($str))));
 	}
 }