diff --git a/.travis.yml b/.travis.yml
index 06e6e012..0551b062 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -9,6 +9,6 @@ install:
     - "`which python3` -m pip install --user flake8"
     - "sudo /usr/bin/python3 -m pip install sgmllib3k"
     - "sudo /usr/bin/python3 -m pip install --upgrade six"
-    - "`which python` -m pip install --user six"
+    - "`which python` -m pip install --upgrade --user six"
     - which python
 script: "sh -x scripts/travis-ci-build"