diff --git a/Gemfile b/Gemfile
index 32921442..81a9bebb 100644
--- a/Gemfile
+++ b/Gemfile
@@ -20,6 +20,8 @@
 # along with this program; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
+source 'https://rubygems.org'
+
 gem 'zip-zip'
 gem 'simple_enum'
 gem 'uuidtools'