diff --git a/resque-scheduler.gemspec b/resque-scheduler.gemspec
index 5f6013d9..0ade74f1 100644
--- a/resque-scheduler.gemspec
+++ b/resque-scheduler.gemspec
@@ -49,7 +49,7 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency 'mocha'
   spec.add_development_dependency 'ostruct'
   spec.add_development_dependency 'pry'
-  spec.add_development_dependency 'rack', '< 3'
+  spec.add_development_dependency 'rack', '< 4'
   spec.add_development_dependency 'rack-test'
   spec.add_development_dependency 'rake'
   spec.add_development_dependency 'simplecov'