diff --git a/context_redirect_reaction.inc b/context_redirect_reaction.inc
index e60dbf7..57e4494 100644
--- a/context_redirect_reaction.inc
+++ b/context_redirect_reaction.inc
@@ -165,7 +165,7 @@ class context_redirect_reaction extends context_reaction {
 
     // Admin key override.
     if ($admin_key = $context->reactions['context_redirect']['admin_key']) {
-      if ($_GET['admin_key'] == $admin_key) {
+      if (isset($_GET['admin_key']) && $_GET['admin_key'] == $admin_key) {
         $valid_redirect = FALSE;
       }
     }