diff --git a/.gitea/workflows/runner-probe.yml b/.gitea/workflows/runner-probe.yml
index 10973fb..b5e8313 100644
--- a/.gitea/workflows/runner-probe.yml
+++ b/.gitea/workflows/runner-probe.yml
@@ -27,8 +27,8 @@ jobs:
         run: |
           set -eu
           if ! command -v docker >/dev/null 2>&1; then
-            echo "docker=missing"
-            exit 0
+            apt-get update -qq
+            DEBIAN_FRONTEND=noninteractive apt-get install -y -qq docker.io
           fi
           docker version --format 'client {{.Client.Version}} / server {{.Server.Version}}'
           docker ps -a --format 'container={{.Names}} status={{.Status}} image={{.Image}}'
@@ -64,12 +64,12 @@ jobs:
             fi
 
             if docker volume inspect lean-bench-books >/dev/null 2>&1; then
-              mountpoint="$(docker volume inspect lean-bench-books --format '{{.Mountpoint}}')"
-              if [ -f "$mountpoint/$target" ]; then
+              if docker run --rm -v lean-bench-books:/books:ro node:16-bullseye \
+                   test -f "/books/$target"; then
                 found=1
                 echo "FOUND volume:lean-bench-books:$target"
-                ls -lh "$mountpoint/$target"
-                sha256sum "$mountpoint/$target" 2>/dev/null || true
+                docker run --rm -v lean-bench-books:/books:ro node:16-bullseye \
+                  sh -c "ls -lh '/books/$target'; sha256sum '/books/$target'"
               fi
             fi
           fi