diff --git a/4.0/test/rack-test-app/Gemfile.lock b/4.0/test/rack-test-app/Gemfile.lock
index 47d6d53e..54882333 100644
--- a/4.0/test/rack-test-app/Gemfile.lock
+++ b/4.0/test/rack-test-app/Gemfile.lock
@@ -6,7 +6,7 @@ GEM
     mustermann (1.1.1)
       ruby2_keywords (~> 0.0.1)
     ostruct (0.6.3)
-    rack (2.2.3)
+    rack (2.2.22)
     rack-protection (2.1.0)
       rack
     ruby2_keywords (0.0.4)