cuba.gemspec in cuba-3.4.0 vs cuba.gemspec in cuba-3.5.0

@@ -1,17 +1,17 @@
 Gem::Specification.new do |s|
   s.name              = "cuba"
-  s.version           = "3.4.0"
+  s.version           = "3.5.0"
   s.summary           = "Microframework for web applications."
   s.description       = "Cuba is a microframework for web applications."
   s.authors           = ["Michel Martens"]
   s.email             = ["[e-mail]"]
   s.homepage          = "https://github.com/soveran/cuba"
   s.license           = "MIT"
 
   s.files = `git ls-files`.split("\n")
 
-  s.add_dependency "rack"
+  s.add_dependency "rack", "~> 1.6.0"
   s.add_development_dependency "cutest"
   s.add_development_dependency "rack-test"
   s.add_development_dependency "tilt"
 end