diff --git a/.travis.yml b/.travis.yml
index 6a378befb1..730f7fd5ee 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -14,7 +14,7 @@ install:
 script:
   - pyflakes pyhf
   - pytest -r sx --ignore tests/benchmarks/ --ignore tests/test_notebooks.py
-  - if [[ $TRAVIS_PYTHON_VERSION == '3.6' ]]; then black --check --verbose .; fi
+  - if [[ $TRAVIS_PYTHON_VERSION == '3.6' ]]; then black --check --diff --verbose .; fi
 after_success: coveralls
 
 # always test (on both 'push' and 'pr' builds in Travis)