diff --git a/Gemfile b/Gemfile
index 4f1df5d..a62e292 100644
--- a/Gemfile
+++ b/Gemfile
@@ -19,7 +19,7 @@ group :development do
 end
 
 group :production do
-  gem 'puma', '~> 2.0'
+  gem 'puma', '~> 4.3'
 end
 
 gem 'sinatra', '~> 1.4.2'
diff --git a/Gemfile.lock b/Gemfile.lock
index c098d89..26dfaf3 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -23,8 +23,10 @@ GEM
     kramdown (0.14.2)
     liquid (2.3.0)
     maruku (0.7.2)
+    nio4r (2.5.2)
     posix-spawn (0.3.9)
-    puma (2.15.3)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     pygments.rb (0.3.7)
       posix-spawn (~> 0.3.6)
       yajl-ruby (~> 1.1.0)
@@ -55,7 +57,7 @@ DEPENDENCIES
   haml (~> 3.1.7)
   jekyll (~> 0.12)
   liquid (~> 2.3.0)
-  puma (~> 2.0)
+  puma (~> 4.3)
   pygments.rb (~> 0.3.4)
   rake
   rb-fsevent (~> 0.9)