diff --git a/.travis.yml b/.travis.yml
index 19f3bf8..c99147e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -19,4 +19,4 @@ script:
 after_success:
 - mv deploy_key ~/.ssh/id_rsa
 - chmod 600 ~/.ssh/id_rsa
-- '$TRAVIS_PULL_REQUEST || [[ $TRAVIS_BRANCH == "master" ]] && bundle exec nanoc deploy public'
+- '[ -z "$TRAVIS_PULL_REQUEST" ] || [[ $TRAVIS_BRANCH == "master" ]] && bundle exec nanoc deploy public'