--- checkout.module.orig	2008-08-06 14:48:53.000000000 +0200
+++ checkout.module	2008-08-06 15:00:00.000000000 +0200
@@ -179,7 +179,7 @@
  *   The user id to (un)lock nodes for.
  */
 function checkout_handle_request($uid) {
-  global $base_path;
+  global $base_path, $language;
   
   // Build referer path
   $referer_uri = parse_url(referer_uri());
@@ -197,6 +197,19 @@
     $referer = drupal_get_normal_path($referer);
   }
 
+  // $_GET['q'] doesn't have a language prefix, referer_uri does (if defined).
+  // Remove it from $referer to enable comparison with $_GET['q'].
+  if (!empty($language->prefix)) {
+    // Check language_negotiation mode because prefix can be defined without
+    // using it in URLs, and someone could define a fixed path starting
+    // with the same string as a language prefix.
+    $mode = variable_get('language_negotiation', LANGUAGE_NEGOTIATION_NONE);
+    switch ($mode) {
+    case LANGUAGE_NEGOTIATION_PATH_DEFAULT:
+    case LANGUAGE_NEGOTIATION_PATH:
+      $referer = preg_replace("?^". $language->prefix ."/?",'',$referer);
+    }
+  }
   // If refering and current paths match we can abort, since there can't be any
   // locking action involved.
   if ($_GET['q'] == $referer) {