diff --git a/rack-attack.gemspec b/rack-attack.gemspec
index a021f10..652c0d2 100644
--- a/rack-attack.gemspec
+++ b/rack-attack.gemspec
@@ -25,17 +25,17 @@ Gem::Specification.new do |s|
 
   s.add_dependency 'rack'
 
-  s.add_development_dependency 'appraisal'
-  s.add_development_dependency 'minitest'
-  s.add_development_dependency "minitest-stub-const"
-  s.add_development_dependency 'rack-test'
-  s.add_development_dependency 'rake'
+  s.add_development_dependency 'appraisal', '~> 2.2'
+  s.add_development_dependency 'minitest', "~> 5.11"
+  s.add_development_dependency "minitest-stub-const", "~> 0.6"
+  s.add_development_dependency 'rack-test', "~> 1.0"
+  s.add_development_dependency 'rake', "~> 12.3"
   s.add_development_dependency "rubocop", "0.57.2"
-  s.add_development_dependency "timecop"
+  s.add_development_dependency "timecop", "~> 0.9.1"
 
   # byebug only works with MRI
   if RUBY_ENGINE == "ruby"
-    s.add_development_dependency 'byebug'
+    s.add_development_dependency 'byebug', '~> 10.0'
   end
 
   # The following are potential runtime dependencies users may have,