diff --git a/.github/workflows/differential-shellcheck.yml b/.github/workflows/differential-shellcheck.yml
index 6f4b69d8a7..4b40d397a3 100644
--- a/.github/workflows/differential-shellcheck.yml
+++ b/.github/workflows/differential-shellcheck.yml
@@ -30,4 +30,6 @@ jobs:
       - name: Differential ShellCheck
         uses: redhat-plumbers-in-action/differential-shellcheck@ac4483d8c6713bd2011037f44fe626989468af74
         with:
+          # exclude all `.in` files because they may contain unsupported syntax, and they have to be preprocessed first
+          exclude-path: '**/*.in'
           token: ${{ secrets.GITHUB_TOKEN }}