diff --git a/jekyll-auth.gemspec b/jekyll-auth.gemspec
index d422556..695ef9a 100644
--- a/jekyll-auth.gemspec
+++ b/jekyll-auth.gemspec
@@ -21,7 +21,7 @@ Gem::Specification.new do |s|
   s.add_dependency "dotenv", "~> 2.0"
   s.add_dependency "jekyll", "~> 4.0"
   s.add_dependency "mercenary", "~> 0.3"
-  s.add_dependency "rack", ">= 1.6", "< 3.0"
+  s.add_dependency "rack", ">= 1.6", "< 4.0"
   s.add_dependency "rack-protection", ">= 1.5.5", "< 3.0"
   s.add_dependency "rack-ssl-enforcer", "~> 0.2"
   s.add_dependency "rake", "~> 13.0"