diff --git a/api/controller/controller_util.py b/api/controller/controller_util.py
index 0cf3a59..0476676 100644
--- a/api/controller/controller_util.py
+++ b/api/controller/controller_util.py
@@ -7,6 +7,7 @@
 import glob
 import logging
 import os
+from pathlib import Path
 from typing import Iterable, Optional, TYPE_CHECKING, Union
 
 from chromite.api.gen.chromite.api import sysroot_pb2
@@ -51,7 +52,7 @@
     path = chroot_message.path or constants.DEFAULT_CHROOT_PATH
     cache_dir = chroot_message.cache_dir
     chrome_root = chroot_message.chrome_dir
-    out_path = chroot_message.out_path or constants.DEFAULT_OUT_PATH
+    out_path = Path(chroot_message.out_path) or constants.DEFAULT_OUT_PATH
 
     use_flags = [u.flag for u in chroot_message.env.use_flags]
     features = [f.feature for f in chroot_message.env.features]