diff --git a/Gemfile.lock b/Gemfile.lock
index 5efd207..4359b77 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -3,27 +3,27 @@ PATH
   specs:
     action_handler (0.2.7)
       activesupport (~> 5.2)
-      rack (~> 2.0)
+      rack (>= 2, < 4)
 
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (5.2.6)
+    activesupport (5.2.8.1)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (>= 0.7, < 2)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
     coderay (1.1.2)
-    concurrent-ruby (1.1.8)
+    concurrent-ruby (1.2.2)
     diff-lcs (1.3)
-    i18n (1.8.10)
+    i18n (1.12.0)
       concurrent-ruby (~> 1.0)
     method_source (0.9.2)
-    minitest (5.14.4)
+    minitest (5.18.0)
     pry (0.12.2)
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
-    rack (2.2.3)
+    rack (3.0.7)
     rake (13.0.1)
     rspec (3.8.0)
       rspec-core (~> 3.8.0)
@@ -39,7 +39,7 @@ GEM
       rspec-support (~> 3.8.0)
     rspec-support (3.8.2)
     thread_safe (0.3.6)
-    tzinfo (1.2.9)
+    tzinfo (1.2.11)
       thread_safe (~> 0.1)
 
 PLATFORMS
diff --git a/action_handler.gemspec b/action_handler.gemspec
index 7c09db6..e550c62 100644
--- a/action_handler.gemspec
+++ b/action_handler.gemspec
@@ -37,5 +37,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "pry", "~> 0.12"
 
   spec.add_runtime_dependency "activesupport", "~> 5.2"
-  spec.add_runtime_dependency "rack", "~> 2.0"
+  spec.add_runtime_dependency "rack", ">= 2", "< 4"
 end