diff --git a/tox.ini b/tox.ini
index d4deebc..21af2a0 100644
--- a/tox.ini
+++ b/tox.ini
@@ -12,7 +12,7 @@ commands =
 
 [testenv:black]
 deps = .[lint]
-commands = python -m black --check .
+commands = python -m black --diff --check .
 
 [testenv:check-manifest]
 deps = .[lint]