diff --git a/Gemfile.lock b/Gemfile.lock
index 2e96a19..b90903b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -3,7 +3,7 @@ PATH
   specs:
     optimism (0.3.5)
       cable_ready (>= 4.4.6)
-      rack (~> 2.0)
+      rack (>= 2, < 4)
       rails (>= 5.2)
 
 GEM
@@ -96,6 +96,8 @@ GEM
     nokogiri (1.13.9)
       mini_portile2 (~> 2.8.0)
       racc (~> 1.4)
+    nokogiri (1.13.9-x64-mingw32)
+      racc (~> 1.4)
     parallel (1.19.1)
     parser (2.7.0.2)
       ast (~> 2.4.0)
@@ -105,7 +107,7 @@ GEM
     pry-nav (0.3.0)
       pry (>= 0.9.10, < 0.13.0)
     racc (1.6.0)
-    rack (2.2.3)
+    rack (2.2.6.2)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
     rails (6.1.4.1)
diff --git a/optimism.gemspec b/optimism.gemspec
index 87372c9..c2f2e7b 100644
--- a/optimism.gemspec
+++ b/optimism.gemspec
@@ -25,7 +25,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "pry", "~> 0.12.2"
   spec.add_development_dependency "pry-nav", "~> 0.3.0"
   spec.add_development_dependency "standardrb", "~> 1.0.0"
-  spec.add_dependency "rack", "~> 2.0"
+  spec.add_dependency "rack", ">= 2", "< 4"
   spec.add_dependency "rails", [">= 5.2"]
   spec.add_dependency "cable_ready", ">= 4.4.6"
 end