Update README.md

travis-ci · Oct 15, 2016 · e9b71af · e9b71af
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commit e9b71af
Showing 1 changed file with 1 addition and 1 deletion.
diff --git 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: