diff -u b/redirect.admin.inc b/redirect.admin.inc
--- b/redirect.admin.inc
+++ b/redirect.admin.inc
@@ -536,7 +536,7 @@
 
   if (empty($form_state['values']['override'])) {
     // Find out if any (disabled or enabled) redirect with this source already exists.
-    if ($existing = redirect_load_by_source($redirect->source, $redirect_language, array(), FALSE)) {
+    if ($existing = redirect_load_by_source($redirect->source, $redirect->language, array(), FALSE)) {
       if ($redirect->rid != $existing->rid && $redirect->language == $existing->language) {
         // The "from" path should not conflict with another (disabled or
         // enabled) redirect.