From e9b71af5df4b2ac863b3c19f0e7f6494531f776c Mon Sep 17 00:00:00 2001
From: designerror <designerror@yandex.ru>
Date: Sat, 15 Oct 2016 11:10:21 +0400
Subject: [PATCH] Update README.md

---
 README.md | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/README.md b/README.md
index f3e09d1b..68914c48 100644
--- a/README.md
+++ b/README.md
@@ -2012,7 +2012,7 @@ Ubuntu:
     $ sudo apt-get install python-software-properties
     $ sudo apt-add-repository ppa:brightbox/ruby-ng
     $ sudo apt-get update
-    $ sudo apt-get install ruby2.1 ruby-switch
+    $ sudo apt-get install ruby2.1 ruby2.1-dev ruby-switch
     $ sudo ruby-switch --set ruby2.1
 
 Fedora: