diff --git a/Gemfile b/Gemfile
index 646f241..17ad05a 100644
--- a/Gemfile
+++ b/Gemfile
@@ -9,7 +9,7 @@ ruby File.read(".ruby-version").rstrip
 gem "activesupport"
 gem "config"
 gem "mechanize"
-gem "rack", "< 3"
+gem "rack", "< 4"
 gem "roda"
 gem "sidekiq"
 gem "slack-ruby-client"
diff --git a/Gemfile.lock b/Gemfile.lock
index 34937ba..000e96d 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -108,7 +108,7 @@ GEM
       method_source (~> 1.0)
     public_suffix (6.0.0)
     racc (1.8.0)
-    rack (2.2.9)
+    rack (3.1.7)
     rainbow (3.1.1)
     rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
@@ -181,7 +181,7 @@ DEPENDENCIES
   guard
   guard-rspec
   mechanize
-  rack (< 3)
+  rack (< 4)
   roda
   rspec (~> 3.12)
   rubocop