diff --git a/sync.sh b/sync.sh
index 0e0ff4c..cef68ca 100755
--- a/sync.sh
+++ b/sync.sh
@@ -4,5 +4,6 @@ BRANCH='3.4'
 echo ">>>> Checkout branch $BRANCH"
 git checkout $BRANCH
 git submodule init
+git submodule foreach git reset --hard HEAD
 git submodule foreach git checkout $BRANCH
 git submodule update --remote