diff --git a/authfs/service/src/authfs.rs b/authfs/service/src/authfs.rs
index 3e8e0e0..cfd5766 100644
--- a/authfs/service/src/authfs.rs
+++ b/authfs/service/src/authfs.rs
@@ -176,7 +176,7 @@
             bail!("Child has exited: {}", exit_status);
         }
         if start_time.elapsed() > AUTHFS_SETUP_TIMEOUT_SEC {
-            let _ = child.kill();
+            let _ignored = child.kill();
             bail!("Time out mounting authfs");
         }
         sleep(AUTHFS_SETUP_POLL_INTERVAL_MS);