diff --git a/.travis.yml b/.travis.yml
index 24df43713b0d..77fafa781be6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -8,7 +8,7 @@ matrix:
     - python: "3.6"
       env: TEST_CMD="./tests/mypy_selftest.py"
     - python: "3.5"
-      env: TEST_CMD="./tests/mypy_test.py --no-implicit-optional"
+      env: TEST_CMD="./tests/mypy_test.py --no-implicit-optional --no-site-packages"
     - python: "2.7"
       env: TEST_CMD="./tests/pytype_test.py --num-parallel=4"
       sudo: true