diff --git a/.travis.yml b/.travis.yml
index b76b7b49..21dcbf35 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,6 +1,8 @@
 language: cpp
 addons:
   apt:
+    sources:
+    - ubuntu-toolchain-r-test
     packages:
     - g++-4.8
     - php5-cli