diff --git a/README.md b/README.md
index c5e1b41..247ebde 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,7 @@
-spark-rc
-========
+# spark-rc
 
 A simple rc script to kickstart your system.
+
+## depends
+
+* Enabled sysrq or halt from suckless.org's ubase.
diff --git a/rc.in b/rc.in
index 12002e9..1e43f89 100644
--- a/rc.in
+++ b/rc.in
@@ -128,10 +128,21 @@ rc.boot() {
 }
 
 rc.halt() {
+	if type -P halt; then
+		function rc.halt_poweroff { halt -p; }
+		function rc.halt_reboot { halt -r; }
+	elif [[ -f /proc/sysrq-trigger ]]; then
+		function rc.halt_poweroff { echo 'o' > /proc/sysrq-trigger; }
+		function rc.halt_reboot { echo 'b' > /proc/sysrq-trigger; }
+	else
+		printf 'Cannot halt, please install halt from suckless.org ubase or enable sysrq.\n'
+		return 1
+	fi
+
 	case "$action" in
-		poweroff|shutdown) echo 'o' > /proc/sysrq-trigger;;
 		halt) :;;
-		reboot|*) echo 'b' > /proc/sysrq-trigger;;
+		poweroff|shutdown) rc.halt_poweroff;;
+		reboot|*) rc.halt_reboot;;
 	esac
 }