diff --git a/Gemfile.lock b/Gemfile.lock
index e6b3ac7..422725d 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -10,7 +10,7 @@ GEM
     eventmachine (1.0.1)
     haml (4.0.0)
       tilt
-    rack (1.5.2)
+    rack (2.1.4.1)
     rspec (2.14.1)
       rspec-core (~> 2.14.0)
       rspec-expectations (~> 2.14.0)
diff --git a/pssh.gemspec b/pssh.gemspec
index a8d54eb..fd153ca 100644
--- a/pssh.gemspec
+++ b/pssh.gemspec
@@ -15,7 +15,7 @@ Gem::Specification.new do |gem|
   gem.version       = Pssh::VERSION
 
   gem.add_dependency 'json', '~> 1.8.0'
-  gem.add_dependency 'rack', '~> 1.5.2'
+  gem.add_dependency 'rack', '>= 1.5.2', '< 2.3.0'
   gem.add_dependency 'thin', '~> 1.5.0'
   gem.add_dependency 'websocket-rack', '~> 0.4.0'
   gem.add_dependency 'haml', '~> 4.0.0'