diff --git a/futurism.gemspec b/futurism.gemspec
index aeaebdf..eb006fc 100644
--- a/futurism.gemspec
+++ b/futurism.gemspec
@@ -29,7 +29,8 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "standardrb"
   spec.add_development_dependency "sqlite3"
 
-  spec.add_dependency "rack", "~> 2.0"
+  spec.add_dependency "rack", ">= 2", "< 4"
+
   spec.add_dependency "rails", ">= 5.2"
   spec.add_dependency "cable_ready", ">= 5.0"
 end