diff --git a/src/Build/TreeFactory.php b/src/Build/TreeFactory.php
index 694ec8e..415020a 100644
--- a/src/Build/TreeFactory.php
+++ b/src/Build/TreeFactory.php
@@ -138,6 +138,6 @@ private function getCacheFile(string $kernelCacheDirectory, RequestStack $reques
             $cacheDirectory .= $mainRequest->getHttpHost().'/';
         }
 
-        return $cacheDirectory . 'tree.php';
+        return $cacheDirectory.'tree.php';
     }
 }