diff --git a/.travis.yml b/.travis.yml
index a17f242d1..35c9932f7 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -10,6 +10,19 @@ compiler:
 before_install:
   - ./scripts/test.sh deps
   - ./scripts/test.sh pydeps
+  # use clang 4.0 instead of 3.9 due to unnecessary va_start() warnings
+  - echo $TRAVIS_OS_NAME
+  - echo $CC
+  - echo $(clang --version)
+  - if [ "$TRAVIS_OS_NAME" == "linux" -a "$CC" == "clang" ]; then
+      if [[ "$(clang --version)" =~ 3\.9\.[0-9] ]]; then
+        curl http://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -;
+        echo "deb http://apt.llvm.org/trusty/ llvm-toolchain-trusty-4.0 main" | sudo tee -a /etc/apt/sources.list;
+        sudo apt-get update -qq;
+        sudo apt-get install -qq clang-4.0;
+        CC=clang-4.0;
+      fi;
+    fi
 
 before_script:
   - sudo sysctl -w net.ipv6.conf.all.disable_ipv6=0 || true