diff --git a/advanced/DispatchGroup/sinatra/Gemfile.lock b/advanced/DispatchGroup/sinatra/Gemfile.lock
index 989d1a36..8d21ad7e 100644
--- a/advanced/DispatchGroup/sinatra/Gemfile.lock
+++ b/advanced/DispatchGroup/sinatra/Gemfile.lock
@@ -3,7 +3,7 @@ GEM
   specs:
     mustermann (1.1.1)
       ruby2_keywords (~> 0.0.1)
-    rack (2.2.3)
+    rack (2.2.6.4)
     rack-protection (2.2.0)
       rack
     ruby2_keywords (0.0.5)