diff --git a/build.sh b/build.sh
index d71ed15..68793c9 100755
--- a/build.sh
+++ b/build.sh
@@ -11,7 +11,7 @@ IMAGE="${IMAGE_REPO:-localhost/opencode-dev}"
 
 usage() {
   echo 'Usage: $0 [--no-cache] [--update] [--dry-run] [--remove] [--prune] [--apt-packages="pack1 pack2"]'
-  exit 2
+  exit "${1:-0}"
 }
 
 BUILD_OPTS=()
@@ -31,7 +31,7 @@ while (($#)); do
                 read -ra _pkgs <<< "${1#*=}"
                 EXTRA_APT_PACKAGES="${_pkgs[@]}" ;;
     -h|--help)  usage ;;
-    *) echo "Unknown option: $1" >&2; usage ;;
+    *) echo "Unknown option: $1" >&2; usage 2 ;;
   esac
   shift
 done