diff --git a/.travis.yml b/.travis.yml
index 54cd25c6..b96f2181 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -104,6 +104,7 @@ matrix:
           compiler: clang
           #clang version 3.5.0 (tags/RELEASE_350/final)
         - os: linux
+          addons:
             apt:
               sources:
               - llvm-toolchain-precise-3.5
@@ -117,6 +118,7 @@ matrix:
           compiler: clang
           #
         - os: linux
+          addons:
             apt:
               sources:
               - llvm-toolchain-precise-3.6
@@ -130,6 +132,7 @@ matrix:
           compiler: clang
           #
         - os: linux
+          addons:
             apt:
               sources:
               - llvm-toolchain-precise-3.7
@@ -143,6 +146,7 @@ matrix:
           compiler: clang
           #
         - os: linux
+          addons:
             apt:
               sources:
               - llvm-toolchain-precise-3.8