diff --git a/.travis.yml b/.travis.yml
index 67f9de5e8227f64448ab58f88e78ed93b861d3f8..c02ba146db1441958a5cac91da3ecf863bbd1feb 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -18,5 +18,6 @@ install:
 script:
   - pwd
   - ls -la
+  - if [[ "${TRAVIS_TAG}" == "" ]]; then unset TWINE_USERNAME; fi
   - docker run --rm -v `pwd`:/io -e TWINE_USERNAME -e TWINE_PASSWORD $DOCKER_IMAGE $PRE_CMD /io/travis/build-wheels.sh
   - ls wheelhouse/