diff --git a/.travis.yml b/.travis.yml
index a91f1884..017917dd 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,9 +12,11 @@ matrix:
       addons:
         apt:
           sources:
+          - ubuntu-toolchain-r-test
           - llvm-toolchain-trusty-6.0
           packages:
           - clang-6.0
+          - g++-7
       env:
       - MATRIX_EVAL="CC=clang-6.0 && CXX=clang++-6.0"