diff --git a/classes/Validate.php b/classes/Validate.php
index 942a0574a..a3e564f1b 100644
--- a/classes/Validate.php
+++ b/classes/Validate.php
@@ -472,9 +472,9 @@ class ValidateCore
 	 */
 	public static function isDate($date)
 	{
-		if (!preg_match('/^([0-9]{4})-((0?[0-9])|(1[0-2]))-((0?[0-9])|([1-2][0-9])|(3[01]))( [0-9]{2}:[0-9]{2}:[0-9]{2})?$/', $date, $matches))
+		if (!preg_match('/^([0-9]{4})-((?:0?[0-9])|(?:1[0-2]))-((?:0?[0-9])|(?:[1-2][0-9])|(?:3[01]))( [0-9]{2}:[0-9]{2}:[0-9]{2})?$/', $date, $matches))
 			return false;
-		return checkdate((int)$matches[2], (int)$matches[5], (int)$matches[0]);
+		return checkdate((int)$matches[2], (int)$matches[3], (int)$matches[1]);
 	}
 
 	/**