diff --git a/.travis.yml b/.travis.yml
index e9f31210..ae7d5249 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -40,7 +40,7 @@ script:
 after_success:
   - codecov
   - cd doc
-  - sphinx-apidoc -o source ../GPy
+  - "sphinx-apidoc -o source ../GPy"
   - make html
   - cd ../