diff --git a/scripts/heroku/prebuild.sh b/scripts/heroku/prebuild.sh
index aafaf4b6..f280b8dd 100755
--- a/scripts/heroku/prebuild.sh
+++ b/scripts/heroku/prebuild.sh
@@ -3,6 +3,11 @@ echo "Fetch Submodules"
 git clone --depth 1 https://github.com/ohmyform/ui ui
 git clone --depth 1 https://github.com/ohmyform/api api
 
+echo "UI ref is"
+git --git-dir=ui/.git rev-parse HEAD
+echo "API ref is"
+git --git-dir=api/.git rev-parse HEAD
+
 echo "Install UI"
 yarn --cwd ui install --frozen-lockfile