diff --git a/Gemfile b/Gemfile
index 0bb6ab56d..c710ff0df 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,4 +1,4 @@
-source 'http://rubygems.org'
+source 'https://rubygems.org'
 
 if Gem::Version.new(Bundler::VERSION) < Gem::Version.new('1.5.0')
   abort "Redmine requires Bundler 1.5.0 or higher (you're using #{Bundler::VERSION}).\nPlease update with 'gem update bundler'."