diff --git a/2019/s4/aspost/Gemfile.lock b/2019/s4/aspost/Gemfile.lock
index c8382a3..c2cf8fd 100644
--- a/2019/s4/aspost/Gemfile.lock
+++ b/2019/s4/aspost/Gemfile.lock
@@ -106,7 +106,7 @@ GEM
     pg (1.1.4)
     public_suffix (4.0.1)
     puma (3.12.1)
-    rack (2.0.7)
+    rack (2.2.6.2)
     rack-proxy (0.6.5)
       rack
     rack-test (1.1.0)