diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index 24f4b90..7ec4f2e 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -23,7 +23,7 @@ jobs:
        lfs: True
     
     # Building as html.
-    - uses: ammaraskar/sphinx-action@master
+    - uses: ammaraskar/sphinx-action@8.1.3
       with:
         docs-folder: "docs/"