diff --git a/.github/workflows/publish_api_documentation.yml b/.github/workflows/publish_api_documentation.yml
index 199ea349..32663ec4 100644
--- a/.github/workflows/publish_api_documentation.yml
+++ b/.github/workflows/publish_api_documentation.yml
@@ -15,7 +15,7 @@ jobs:
     steps:
     - uses: actions/checkout@v2
       with:
-        ref: 3.0
+        ref: "3.0"
     - uses: actions/setup-python@v2
       with:
         python-version: 3.6