diff --git a/src/Route.php b/src/Route.php
index 16bf99e..00f0b84 100755
--- a/src/Route.php
+++ b/src/Route.php
@@ -169,7 +169,7 @@ private function substituteFilter($matches)
     private function validateFilters()
     {
         foreach($this->filters as $key => $reg) {
-            if(!preg_match('~^:([[a-z]])$~i', $key)) {
+            if(!preg_match('~^:([a-z]+)$~i', $key)) {
                 throw new Exception('Invalid filter name `'.$key.'` it should contains only letters and start with `:`');
             }
         }