diff --git a/includes/utilities.php b/includes/utilities.php
index 41287c44..6996f1ce 100644
--- a/includes/utilities.php
+++ b/includes/utilities.php
@@ -1497,6 +1497,26 @@ class Util
         return $return;
     }
 
+    public static function isValidPage($struct, $keys)
+    {
+        switch (count($keys))
+        {
+            case 0:
+                return true;
+            case 1:
+                return !$keys[0] || isset($struct[$keys[0]]);
+            case 2:
+                if (!isset($struct[$keys[0]]))
+                    return false;
+
+                return in_array($keys[1], $struct[$keys[0]]) || isset($struct[$keys[0]][$keys[1]]);
+            case 3:
+                return isset($struct[$keys[0]][$keys[1]]) && in_array($keys[2], $struct[$keys[0]][$keys[1]]);
+        }
+
+        return false;
+    }
+
     // BaseType::_construct craaap!
     // todo: unify names
     public static function getNameFieldName($tpl)
diff --git a/pages/achievements.php b/pages/achievements.php
index 0a5d592b..692428ea 100644
--- a/pages/achievements.php
+++ b/pages/achievements.php
@@ -36,22 +36,7 @@ $validCats  = array(
     )
 );
 
-$valid = false;
-switch (count($cats))
-{
-    case 0:
-        $valid = true;
-    case 1:
-        $valid = !$cats[0] || isset($validCats[$cats[0]]);
-        break;
-    case 2:
-        $valid = $cats[0] == 1 ? isset($validCats[$cats[0]][$cats[1]]) : isset($validCats[$cats[0]]) && in_array($cats[1], $validCats[$cats[0]]);
-        break;
-    case 3:
-        $valid = $cats[0] == 1 ? isset($validCats[$cats[0]][$cats[1]]) && in_array($cats[2], $validCats[$cats[0]][$cats[1]]) : false;
-        break;
-}
-if (!$valid)
+if (!Util::isValidPage($validCats, $cats))
     $smarty->error();
 
 if (!$smarty->loadCache($cacheKey, $pageData))