Try .travis.yml

.travis.yml

@@ -2,15 +2,17 @@ language: node_js
 node_js:
   - 6.9.2
 before_install:
-  - sudo add-apt-repository ppa:ubuntu-toolchain-r/test -y
-  - sudo apt-get install gcc-4.9 g++-4.9
-  - export CXX=g++-4.9
+  - if [ "$CXX" = "g++" ]; then export CXX="g++-4.9" CC="gcc-4.9"; fi
 addons:
   apt:
+    sources:
+      - ubuntu-toolchain-r-test
     packages:
       - pkg-config
       - libcairo2-dev
       - libpango1.0-dev
       - libjpeg8-dev
       - libgif-dev
+      - gcc-4.9
+      - g++-4.9
 sudo: false