diff --git a/docs/Gemfile b/docs/Gemfile
old mode 100755
new mode 100644
index 67a07a1..c6165c7
--- a/docs/Gemfile
+++ b/docs/Gemfile
@@ -10,4 +10,4 @@ gem "middleman-sprockets", "~> 4.1.0"
 gem 'rouge', '~> 2.0.5'
 gem 'redcarpet', '~> 3.4.0'
 gem 'nokogiri', '~> 1.6.8'
-gem 'puma', '~> 3.4'
+gem 'puma', '~> 4.3'
diff --git a/docs/Gemfile.lock b/docs/Gemfile.lock
old mode 100755
new mode 100644
index 067bae4..fbe3af3
--- a/docs/Gemfile.lock
+++ b/docs/Gemfile.lock
@@ -81,6 +81,7 @@ GEM
       rouge (~> 2.0)
     mini_portile2 (2.1.0)
     minitest (5.10.1)
+    nio4r (2.5.8)
     nokogiri (1.6.8.1)
       mini_portile2 (~> 2.1.0)
     padrino-helpers (0.13.3.3)
@@ -91,7 +92,8 @@ GEM
       activesupport (>= 3.1)
     parallel (1.10.0)
     public_suffix (2.0.5)
-    puma (3.11.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.1)
     rake (11.3.0)
     rb-fsevent (0.9.8)
@@ -121,7 +123,7 @@ DEPENDENCIES
   middleman-sprockets (~> 4.1.0)
   middleman-syntax (~> 3.0.0)
   nokogiri (~> 1.6.8)
-  puma (~> 3.4)
+  puma (~> 4.3)
   rake (~> 11.1)
   redcarpet (~> 3.4.0)
   rouge (~> 2.0.5)