diff --git a/book/Gemfile.lock b/book/Gemfile.lock
index 7bcd1e6..bd49bc5 100644
--- a/book/Gemfile.lock
+++ b/book/Gemfile.lock
@@ -167,7 +167,7 @@ GEM
     parallel (1.12.1)
     public_suffix (3.0.1)
     puma (3.11.2)
-    rack (1.6.8)
+    rack (1.6.13)
     rack-livereload (0.3.16)
       rack
     rack-rewrite (1.5.1)