diff --git a/Gemfile b/Gemfile
index 05ce24e..125f0ea 100644
--- a/Gemfile
+++ b/Gemfile
@@ -2,10 +2,10 @@
 # the following line to use "https"
 source 'http://rubygems.org'
 
-gem "middleman", "~>3.3.3"
+gem "middleman", "~> 4.3.7"
 
 # Live-reloading plugin
-gem "middleman-livereload", "~> 3.1.0"
+gem "middleman-livereload", "~> 3.1.1"
 
 # For faster file watcher updates on Windows:
 gem "wdm", "~> 0.1.0", :platforms => [:mswin, :mingw]
@@ -21,4 +21,4 @@ gem "haml"
 # Heroku
 ruby "2.1.0"
 gem "rack-contrib"
-gem "puma"
+gem "puma", ">= 3.12.6"