diff --git a/lighthouse-core/test/chromium-web-tests/download-devtools.sh b/lighthouse-core/test/chromium-web-tests/download-devtools.sh
index efe8e2e4bf9b..7555403325b2 100644
--- a/lighthouse-core/test/chromium-web-tests/download-devtools.sh
+++ b/lighthouse-core/test/chromium-web-tests/download-devtools.sh
@@ -14,8 +14,10 @@ then
   cd "$DEVTOOLS_PATH"
 
   # Update to keep current
+  git reset --hard
+  git clean -fd
   git pull -f origin master
-  gclient sync
+  gclient sync --delete_unversioned_trees --reset
 
   exit 0
 fi