diff --git a/Chapter02/pichat-api-attachments-service/Gemfile.lock b/Chapter02/pichat-api-attachments-service/Gemfile.lock
index e7997df..c3a6020 100644
--- a/Chapter02/pichat-api-attachments-service/Gemfile.lock
+++ b/Chapter02/pichat-api-attachments-service/Gemfile.lock
@@ -96,7 +96,7 @@ GEM
     nokogiri (1.8.1)
       mini_portile2 (~> 2.3.0)
     puma (3.10.0)
-    rack (2.0.3)
+    rack (2.2.3)
     rack-test (0.7.0)
       rack (>= 1.0, < 3)
     rails (5.1.4)