diff --git a/src/Generator.php b/src/Generator.php
index 9eb47d3..a5662d7 100644
--- a/src/Generator.php
+++ b/src/Generator.php
@@ -65,6 +65,10 @@ private function allocateLocaleArray($path)
      */
     private function adjustString($s)
     {
+        if (!is_string($s)) {
+            return $s;
+        }
+
         return preg_replace_callback(
             '/:\w*/',
             function ($matches) {