diff --git a/lib/github-markup.rb b/lib/github-markup.rb
index 4b064e0e..df6aa41d 100644
--- a/lib/github-markup.rb
+++ b/lib/github-markup.rb
@@ -1,6 +1,6 @@
 module GitHub
   module Markup
-    VERSION = '3.0.5'
+    VERSION = '4.0.0'
     Version = VERSION
   end
 end
diff --git a/lib/github/markups.rb b/lib/github/markups.rb
index 0ed55df0..f12fb7e0 100644
--- a/lib/github/markups.rb
+++ b/lib/github/markups.rb
@@ -49,7 +49,7 @@
 
 command(
   ::GitHub::Markups::MARKUP_RST,
-  "python2 -S #{Shellwords.escape(File.dirname(__FILE__))}/commands/rest2html",
+  "python3 -S #{Shellwords.escape(File.dirname(__FILE__))}/commands/rest2html",
   /re?st(\.txt)?/,
   ["reStructuredText"],
   "restructuredtext"