diff --git a/.github/workflows/manifest.yml b/.github/workflows/manifest.yml
index c36c721..79b9695 100644
--- a/.github/workflows/manifest.yml
+++ b/.github/workflows/manifest.yml
@@ -42,7 +42,7 @@ jobs:
         uses: actions/checkout@v3
         with:
           ref: 'main'
-          clean: false
+          clean: 'false'
       - name: Generate manifest and shields for main branch
         id: manifest-main
         if: ${{ steps.checkout-main.outcome }} == 'success'
@@ -57,7 +57,7 @@ jobs:
         uses: actions/checkout@v3
         with:
           ref: 'latest'
-          clean: false
+          clean: 'false'
       - name: Generate manifest for latest
         id: manifest-latest
         if: ${{ steps.checkout-latest.outcome }} == 'success'
@@ -72,7 +72,7 @@ jobs:
         uses: actions/checkout@v3
         with:
           ref: 'devel'
-          clean: false
+          clean: 'false'
       - name: Generate manifest for devel
         id: manifest-devel
         if: ${{ (success() || failure()) && steps.checkout-devel.outcome == 'success' }}