diff --git a/Gemfile.lock b/Gemfile.lock
index 5caf9d6..a7bc5a0 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -149,7 +149,7 @@ GEM
       thread_safe (~> 0.3, >= 0.3.1)
     method_source (0.9.2)
     nenv (0.3.0)
-    nio4r (2.5.2)
+    nio4r (2.5.8)
     notiffany (0.1.3)
       nenv (~> 0.1)
       shellany (~> 0.0)
@@ -164,7 +164,7 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     psych (3.1.0)
-    puma (4.3.1)
+    puma (5.6.2)
       nio4r (~> 2.0)
     r18n-core (3.2.0)
     rack (2.0.8)
@@ -286,7 +286,7 @@ DEPENDENCIES
   guard-bundler (~> 2.1)
   guard-rspec (~> 4.7, >= 4.7.3)
   guard-rubocop (~> 1.3)
-  puma (~> 4.3)
+  puma (~> 5.6)
   shotgun (~> 0.9.2)
 
 RUBY VERSION
diff --git a/syscase.gemspec b/syscase.gemspec
index 2e46ace..e5da679 100644
--- a/syscase.gemspec
+++ b/syscase.gemspec
@@ -39,6 +39,6 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency 'guard-bundler',  '~> 2.1'
   gem.add_development_dependency 'guard-rspec',    '~> 4.7', '>= 4.7.3'
   gem.add_development_dependency 'guard-rubocop',  '~> 1.3'
-  gem.add_development_dependency 'puma',           '~> 4.3'
+  gem.add_development_dependency 'puma',           '~> 5.6'
   gem.add_development_dependency 'shotgun',        '~> 0.9.2'
 end