diff --git a/includes/session.inc b/includes/session.inc
index 84d1983..f791028 100644
--- a/includes/session.inc
+++ b/includes/session.inc
@@ -419,13 +419,16 @@ function drupal_session_regenerate() {
  *
  * @param $sid
  *   Session ID.
+ *
+ * @return
+ *   FALSE if writing session data has been disabled. Otherwise, TRUE.
  */
 function _drupal_session_destroy($sid) {
   global $user, $is_https;
 
   // Nothing to do if we are not allowed to change the session.
   if (!drupal_save_session()) {
-    return;
+    return FALSE;
   }
 
   // Delete session data.
@@ -446,6 +449,8 @@ function _drupal_session_destroy($sid) {
   elseif (variable_get('https', FALSE)) {
     _drupal_session_delete_cookie('S' . session_name(), TRUE);
   }
+
+  return TRUE;
 }
 
 /**