diff --git a/.travis.yml b/.travis.yml
index a9bbd44..98e11a5 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -21,10 +21,13 @@ matrix:
       addons: { apt: { packages: ["g++-8"], sources: ["ubuntu-toolchain-r-test"] } }
 
     - env: MATRIX_EVAL="CC=clang-5.0 && CXX=clang++-5.0 && GENERATOR='Unix Makefiles'"
-      addons: { apt: { packages: ["clang-5.0"], sources: ["ubuntu-toolchain-r-test"] } }
+      addons: { apt: { packages: ["clang-5.0"] } }
 
     - env: MATRIX_EVAL="CC=clang-6.0 && CXX=clang++-6.0 && GENERATOR='Unix Makefiles'"
-      addons: { apt: { packages: ["clang-6.0"], sources: ["ubuntu-toolchain-r-test"] } }
+      addons: { apt: { packages: ["clang-6.0"] } }
+
+    - env: MATRIX_EVAL="CC=clang-7.0 && CXX=clang++-7.0 && GENERATOR='Unix Makefiles'"
+      addons: { apt: { packages: ["clang-7.0"], sources: ["llvm-toolchain-xenial-7"] } }
 
     - os: osx
       env: MATRIX_EVAL="CC=clang && CXX=clang++ && GENERATOR=Xcode"