diff --git a/flipped-demos/ch03-saas/ttt/Gemfile.lock b/flipped-demos/ch03-saas/ttt/Gemfile.lock
index 4d68845..a220f1a 100644
--- a/flipped-demos/ch03-saas/ttt/Gemfile.lock
+++ b/flipped-demos/ch03-saas/ttt/Gemfile.lock
@@ -64,7 +64,7 @@ GEM
       racc (~> 1.4)
     public_suffix (5.0.0)
     racc (1.6.0)
-    rack (3.1.7)
+    rack (3.1.21)
     rack-protection (4.0.0)
       base64 (>= 0.1.0)
       rack (>= 3.0.0, < 4)
@@ -72,9 +72,6 @@ GEM
       rack (>= 3.0.0)
     rack-test (2.0.2)
       rack (>= 1.3)
-    rackup (2.1.0)
-      rack (>= 3)
-      webrick (~> 1.8)
     rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
@@ -110,13 +107,13 @@ GEM
       extlib (>= 0.9.5)
       highline (>= 1.4.0)
     tilt (2.4.0)
-    webrick (1.8.1)
     xpath (3.2.0)
       nokogiri (~> 1.8)
 
 PLATFORMS
   arm64-darwin-23
   x86_64-darwin-24
+  x86_64-linux
 
 DEPENDENCIES
   byebug
@@ -125,7 +122,6 @@ DEPENDENCIES
   cucumber-sinatra
   launchy
   rack-test
-  rackup
   rerun
   rspec
   rspec-autotest