diff --git a/.travis.yml b/.travis.yml
index 408e1ab..7cc2955 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -157,6 +157,7 @@ matrix:
         apt:
           packages:
             - clang-4.0
+            - libstdc++-4.9-dev
           sources:
             - ubuntu-toolchain-r-test
             - llvm-toolchain-trusty-4.0
@@ -168,6 +169,7 @@ matrix:
         apt:
           packages:
             - clang-5.0
+            - libstdc++-4.9-dev
           sources:
             - ubuntu-toolchain-r-test
             - llvm-toolchain-trusty-5.0