diff --git a/module/VuFind/src/VuFind/Config/Reader/CacheDecorator.php b/module/VuFind/src/VuFind/Config/Reader/CacheDecorator.php
index 0e487e65628ddc1203b764638ec1f4c110603c95..da9ceffc4ef4e1f939ee3037329c4e82888f4680 100644
--- a/module/VuFind/src/VuFind/Config/Reader/CacheDecorator.php
+++ b/module/VuFind/src/VuFind/Config/Reader/CacheDecorator.php
@@ -81,7 +81,8 @@ class CacheDecorator implements ReaderInterface
      */
     public function fromFile ($filename)
     {
-        $key = $this->generateKey($filename);
+        $mtime = @filemtime(realpath($filename));
+        $key = $this->generateKey($mtime . $filename);
         if ($this->storage->hasItem($key)) {
             return $this->storage->getItem($key);
         }