diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 90da781..a627ba0 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -61,7 +61,7 @@ jobs:
 
       - name: Check by black
         run: |
-          black --check src tests
+          black --check --diff src tests
 
       - name: Check by isort
         run: |