diff --git a/context_reaction_http_header.inc b/context_reaction_http_header.inc
index bef2584..4451035 100644
--- a/context_reaction_http_header.inc
+++ b/context_reaction_http_header.inc
@@ -14,9 +14,11 @@ class context_reaction_http_header extends context_reaction {
     // Retrieve hooked module data
     $items_from_hook = module_invoke_all('context_http_header_def');
     
-    // Get set values from the context for these hooks  
-    foreach ($items_from_hook as $header => $item) {
-      $items_from_hook[$header]['#default_value'] = $values['http_header'][$header];
+    if (!empty($values)) {
+      // Get set values from the context for these hooks  
+      foreach ($items_from_hook as $header => $item) {
+        $items_from_hook[$header]['#default_value'] = $values['http_header'][$header];
+      }
     }
     
     $items['http_header'] = array_merge($items['http_header'], $items_from_hook);