diff --git a/app/services/notifications/reactions/send.rb b/app/services/notifications/reactions/send.rb
index 2d68bd82a..66fbf9341 100644
--- a/app/services/notifications/reactions/send.rb
+++ b/app/services/notifications/reactions/send.rb
@@ -58,7 +58,7 @@ module Notifications
           notification = Notification.find_or_initialize_by(notification_params)
 
           old_json_data = notification.json_data
-          previous_siblings_size = notification.json_data["reaction"]["aggregated_siblings"].size if old_json_data
+          previous_siblings_size = old_json_data.dig("reaction", "aggregated_siblings")&.size if old_json_data
 
           notification.json_data = json_data
           notification.notified_at = Time.current