diff --git a/.github/workflows/build_docs.yml b/.github/workflows/build_docs.yml
index 8fdf2492..f098a46b 100644
--- a/.github/workflows/build_docs.yml
+++ b/.github/workflows/build_docs.yml
@@ -33,7 +33,7 @@ jobs:
           mkdocs build  # twice, see https://github.com/patrick-kidger/pytkdocs_tweaks
 
       - name: Upload docs
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: docs
           path: site  # where `mkdocs build` puts the built site