diff --git a/ratelimitfile.php b/ratelimitfile.php
index e0893aa..efd57e9 100644
--- a/ratelimitfile.php
+++ b/ratelimitfile.php
@@ -25,6 +25,12 @@ class ratelimitfile extends ratelimit
     // Add the current timestamp
     $currentTimeStamp = microtime (true)."\n";
     if ($this->debug) echo "Add entry : $currentTimeStamp";
+    $user = posix_getpwuid (posix_getuid());
+    if (file_exists ($file) && ! is_writeable ($file))
+      throw new \Exception (sprintf (
+                             dgettext("domframework",
+                                      "File '%s' not writeable for user '%s'"),
+                             $file, $user["name"]), 500);
     file_put_contents ($file, $currentTimeStamp, FILE_APPEND);
     $lock = new lockfile ();
     $lock->storagelock = $this->storageDir."/lockfile.lock";