diff --git a/httprl.module b/httprl.module
index f1f3a26..8d759e0 100644
--- a/httprl.module
+++ b/httprl.module
@@ -1740,6 +1740,9 @@ function httprl_post_processing($id, &$responses, &$output, $time_left = NULL) {
   if (   $full_bootstrap
       && !empty($result->options['callback'])
       && is_array($result->options['callback'])
+      && !empty($result->options['callback'][0])
+      && is_array($result->options['callback'][0])
+      && !empty($result->options['callback'][0]['function'])
         ) {
     httprl_run_callback($result);
   }
@@ -1747,6 +1750,9 @@ function httprl_post_processing($id, &$responses, &$output, $time_left = NULL) {
   // Run background_callback.
   if (   !empty($result->options['background_callback'])
       && is_array($result->options['background_callback'])
+      && !empty($result->options['background_callback'][0])
+      && is_array($result->options['background_callback'][0])
+      && !empty($result->options['background_callback'][0]['function'])
         ) {
     httprl_queue_background_callback($result->options['background_callback'], $result);
   }