diff --git a/system/libraries/Validation.php b/system/libraries/Validation.php
index c28713c..79ab76c 100644
--- a/system/libraries/Validation.php
+++ b/system/libraries/Validation.php
@@ -518,7 +518,7 @@
 	 */	
 	function alpha_numeric($str)
 	{
-		return ( ! preg_match("/^([-a-z0-9])+$/i", $str)) ? FALSE : TRUE;
+		return ( ! preg_match("/^([a-z0-9])+$/i", $str)) ? FALSE : TRUE;
 	}
 	
 	// --------------------------------------------------------------------