diff --git a/src/OneSignalClient.php b/src/OneSignalClient.php
index 1a18adf..a9bae1a 100644
--- a/src/OneSignalClient.php
+++ b/src/OneSignalClient.php
@@ -388,7 +388,7 @@ public function sendNotificationCustom($parameters = []){
         }
 
         // Make sure to use included_segments
-        if (empty($parameters['included_segments']) && empty($parameters['include_player_ids']) && empty('include_external_user_ids')) {
+        if (empty($parameters['included_segments']) && empty($parameters['include_player_ids']) && empty($parameters['include_external_user_ids'])) {
             $parameters['included_segments'] = ['All'];
         }