diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index cf9720e..2d8b1a8 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -12,12 +12,12 @@ jobs:
     strategy:
       matrix:
         os:
-        - Windows-2019
-        - Windows-2022
-        - macOS-11
-        - macOS-12
-        - Ubuntu-20.04
-        - Ubuntu-22.04
+        - windows-2019
+        - windows-2022
+        - macos-11
+        - macos-12
+        - ubuntu-20.04
+        - ubuntu-22.04
         nodejs:
         - 16
       fail-fast: false
@@ -34,5 +34,7 @@ jobs:
       run: npm ci
     - name: Build
       run: npm run build
+    - name: Exit if differ (forgot to commit dist dir?)
+      run: git diff --exit-code --quiet
     - name: Verify
       run: npm run verify