diff --git a/2013-JAX/Gemfile b/2013-JAX/Gemfile
index aa8531f..b2470c0 100644
--- a/2013-JAX/Gemfile
+++ b/2013-JAX/Gemfile
@@ -7,7 +7,7 @@ gem 'slim', '~> 2.0.0'
 gem 'less', '~> 2.3.1'
 gem 'therubyracer', '~> 0.11.4'
 gem 'rb-inotify', '~> 0.9.0'
-gem 'puma', '~> 1.6.3' # for a leaner deve server
+gem 'puma', '~> 4.3.11' # for a leaner deve server
 gem 'guard-livereload'
 gem 'yajl-ruby'
 gem 'coffee-script'
diff --git a/2013-JAX/Gemfile.lock b/2013-JAX/Gemfile.lock
index 2e91c1d..0b5a0f5 100644
--- a/2013-JAX/Gemfile.lock
+++ b/2013-JAX/Gemfile.lock
@@ -69,15 +69,16 @@ GEM
     method_source (0.8.1)
     mime-types (1.23)
     multi_json (1.7.2)
+    nio4r (2.5.8)
     nokogiri (1.5.9)
     open4 (1.3.0)
     pry (0.9.12.1)
       coderay (~> 1.0.5)
       method_source (~> 0.8)
       slop (~> 3.4)
-    puma (1.6.3)
-      rack (~> 1.2)
-    rack (1.5.2)
+    puma (4.3.11)
+      nio4r (~> 2.0)
+    rack (1.5.5)
     rb-inotify (0.9.0)
       ffi (>= 0.5.0)
     redcarpet (2.3.0)
@@ -115,7 +116,7 @@ DEPENDENCIES
   guard-livereload
   htmlcompressor
   less (~> 2.3.1)
-  puma (~> 1.6.3)
+  puma (~> 4.3.11)
   rb-inotify (~> 0.9.0)
   redcarpet (~> 2.3.0)
   slim (~> 2.0.0)