diff --git a/Gemfile b/Gemfile
index 844b219..6cd15d6 100644
--- a/Gemfile
+++ b/Gemfile
@@ -6,7 +6,7 @@ git_source(:github) {|repo_name| "https://github.com/#{repo_name}" }
 
 # gem "rails"
 
-gem "puma", "~> 4.3"
+gem "puma", "~> 5.6"
 
 gem "sinatra", "~> 2.0"
 
diff --git a/Gemfile.lock b/Gemfile.lock
index a00e439..610bdfb 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -4,8 +4,8 @@ GEM
     cowsay (0.3.0)
     mustermann (1.1.1)
       ruby2_keywords (~> 0.0.1)
-    nio4r (2.5.2)
-    puma (4.3.5)
+    nio4r (2.7.0)
+    puma (5.6.8)
       nio4r (~> 2.0)
     rack (2.2.3)
     rack-protection (2.0.8.1)
@@ -23,7 +23,7 @@ PLATFORMS
 
 DEPENDENCIES
   cowsay (~> 0.3.0)
-  puma (~> 4.3)
+  puma (~> 5.6)
   sinatra (~> 2.0)
 
 BUNDLED WITH