diff --git a/build.sh b/build.sh
index 88064f1..683b4d2 100644
--- a/build.sh
+++ b/build.sh
@@ -5,6 +5,10 @@ fi
 if [ -z $CFLAGS ]; then
 	CFLAGS="-s -Os -pedantic -Wall -Wextra"
 fi
+if [ -z $1 ]; then
+	echo $0 "[rootfs / clean]"
+	exit
+fi
 
 echo "ENV: CC: " $CC "| CFLAGS: " $CFLAGS