diff --git a/src/File.php b/src/File.php
index 8515f20..bc29f4e 100644
--- a/src/File.php
+++ b/src/File.php
@@ -507,6 +507,7 @@ class File
     {
       $res = flock ($this->locks[$filename], LOCK_UN);
       fclose ($this->locks[$filename]);
+      unset($this->locks[$filename]);
     }
     return $res;
   }