diff --git a/Gemfile b/Gemfile
index 53a4f4c..510b6c1 100644
--- a/Gemfile
+++ b/Gemfile
@@ -32,4 +32,4 @@ gem 'rake'
 gem "sinatra", "~> 2.0.3"
 gem "redis", "~> 4.0.1"
 gem "connection_pool", "~> 2.2.2"
-gem "puma", "~> 3.11.4"
+gem "puma", "~> 4.3.12"
diff --git a/Gemfile.lock b/Gemfile.lock
index aade578..e2ac1ac 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -33,10 +33,12 @@ GEM
     minima (2.1.1)
       jekyll (~> 3.3)
     mustermann (1.0.2)
+    nio4r (2.5.8)
     pathutil (0.16.1)
       forwardable-extended (~> 2.6)
     public_suffix (3.0.2)
-    puma (3.11.4)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.5)
     rack-protection (2.0.3)
       rack
@@ -67,7 +69,7 @@ DEPENDENCIES
   jekyll (~> 3.6.2)
   jekyll-feed (~> 0.6)
   minima (~> 2.0)
-  puma (~> 3.11.4)
+  puma (~> 4.3.12)
   rake
   redis (~> 4.0.1)
   sinatra (~> 2.0.3)