diff --git a/src/Umami.php b/src/Umami.php
index f14188e..f7a0eca 100644
--- a/src/Umami.php
+++ b/src/Umami.php
@@ -178,8 +178,8 @@ private static function setOptions($part, $options): array
         }
 
         $datesOptions = [
-            'startAt' => formatDate($options['startAt']),
-            'endAt' => formatDate($options['endAt']),
+            'startAt' => formatDate($options['start_at']),
+            'endAt' => formatDate($options['end_at']),
         ];
 
         return array_merge($defaultOptions[$part], array_merge($options, $datesOptions));