diff --git a/b9/lib/package.sh b/b9/lib/package.sh
index ecd87309..db458eda 100644
--- a/b9/lib/package.sh
+++ b/b9/lib/package.sh
@@ -21,6 +21,7 @@ b9_package() {
     local USE_CACHE=1
     
     [ -z "$TREEISH" ] && b9_package_usage
+    [[ $TREEISH =~ -- ]] && b9_package_usage
     shift
     
     local ARG
@@ -195,4 +196,4 @@ _do_check_package() {
     
     MODE=devel
     b9_package origin/master --docker --no-cache
-}
\ No newline at end of file
+}