diff --git a/www/extras/numberCheck.js b/www/extras/numberCheck.js
index 6a5c345ce..d39bab8d9 100644
--- a/www/extras/numberCheck.js
+++ b/www/extras/numberCheck.js
@@ -1,5 +1,5 @@
 function doNumCheck(field) {
-	var valid = "0123456789"
+	var valid = "0123456789-";
         var ok = "yes";
         var temp;
         for (var i=0; i<field.value.length; i++) {