diff --git a/.travis.yml b/.travis.yml
index 193da399a..8b4728c76 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,6 +6,9 @@ dist:
 
 addons:
   apt:
+    sources:
+      - llvm-toolchain-trusty-5.0
+      - ubuntu-toolchain-r-test
     packages:
       - clang-5.0
       - libassimp-dev