diff --git a/docker/sinatra/Gemfile.lock b/docker/sinatra/Gemfile.lock
index 86dabe3..6efc3e6 100644
--- a/docker/sinatra/Gemfile.lock
+++ b/docker/sinatra/Gemfile.lock
@@ -3,7 +3,7 @@ GEM
   specs:
     mustermann (1.1.1)
       ruby2_keywords (~> 0.0.1)
-    rack (2.2.3.1)
+    rack (2.2.6.4)
     rack-protection (2.2.0)
       rack
     ruby2_keywords (0.0.5)