diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 18bf064feccf..c1e17ef67840 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -106,6 +106,9 @@ jobs:
         env:
           BABEL_8_BREAKING: false
           STRIP_BABEL_8_FLAG: true
+      - name: Ensure cwd does not contain uncommitted changes
+        run: |
+          ./scripts/assert-dir-git-clean.sh
       - uses: actions/upload-artifact@v2
         with:
           name: babel-artifact
diff --git a/scripts/assert-dir-git-clean.sh b/scripts/assert-dir-git-clean.sh
new file mode 100755
index 000000000000..de07b02483dd
--- /dev/null
+++ b/scripts/assert-dir-git-clean.sh
@@ -0,0 +1,10 @@
+#!/bin/sh
+
+# Exit code 128 if not in git directory.
+GS=$(git status --porcelain=v2 2>/dev/null)
+GS=$?
+if [ $GS -ne 128 ] || [ $GS -ne 0 ]; then
+  echo "Please re-run \"make build\" and checkout the following changes to git"
+  git status
+  exit 1
+fi