diff --git a/src/Foundation/InstalledApp.php b/src/Foundation/InstalledApp.php
index e25c30e1a..94d8d570f 100644
--- a/src/Foundation/InstalledApp.php
+++ b/src/Foundation/InstalledApp.php
@@ -101,7 +101,7 @@ class InstalledApp implements AppInterface
 
     private function subPath($pathName): string
     {
-        return '/'.$this->config['paths'][$pathName];
+        return '/'.($this->config['paths'][$pathName] ?? $pathName);
     }
 
     /**