diff --git a/build.sh b/build.sh
index a91a46d..5647ba5 100755
--- a/build.sh
+++ b/build.sh
@@ -79,7 +79,7 @@ pushd "$site_path"
 # shellcheck source=/dev/null
 . ./build.conf
 GLUON_AUTOUPDATER_BRANCH="${GLUON_AUTOUPDATER_BRANCH:-experimental}"
-[ "${GLUON_AUTOUPDATER_BRANCH}" = "experimental" ] && GLUON_RELEASE="${GLUON_RELEASE}~exp$(date +%Y%m%d)"
+[ "${GLUON_AUTOUPDATER_BRANCH}" = "experimental" ] && GLUON_RELEASE="${GLUON_RELEASE}~exp${BUILD_DATE:-$(date +%Y%m%d)}"
 export GLUON_RELEASE
 export GLUON_AUTOUPDATER_BRANCH
 export GLUON_SITEDIR="${site_path}"