diff --git a/runner/config.yaml b/runner/config.yaml
index 138e7ca..eb2cc57 100644
--- a/runner/config.yaml
+++ b/runner/config.yaml
@@ -29,7 +29,7 @@ container:
   # containers. The regex matches the full `source:target[:opts]`
   # string, so a permissive prefix is enough.
   valid_volumes:
-    - "^cargoxx-cache-(store|keys):"
+    - "^cargoxx-cache-(store|keys)$"
   docker_host: "unix:///var/run/docker.sock"
   force_pull: false