diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index caee658..18d0df1 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -76,15 +76,17 @@ jobs:
     runs-on: ubuntu-latest
     container:
       image: ${{ matrix.image }}
+      # Composite actions should be manually mounted.
       # See: https://github.com/orgs/community/discussions/53771
       volumes:
         - /home/runner/work/_actions/fortran-lang/setup-fortran/v1:/home/runner/work/_actions/fortran-lang/setup-fortran/v1
-    # https://github.com/actions/checkout/issues/1590#issuecomment-2207052044
+    # Workaround for checkout@v3 on containers.
+    # See: https://github.com/actions/checkout/issues/1590#issuecomment-2207052044
     env:
       ACTIONS_ALLOW_USE_UNSECURE_NODE_VERSION: true
     steps:
       - name: Checkout the repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v4
 
       # fortran-lang/setup-fortran requires sudo on Ubuntu.
       - name: Create a dummy sudo