diff --git a/light.sh b/light.sh
index a2e3dbc..68d30f3 100755
--- a/light.sh
+++ b/light.sh
@@ -1,10 +1,12 @@
 #!/bin/bash
 
 TMPFILE_BASE=/tmp/light_state
+TMPFILE_CUSTOM_BASE=/tmp/light_state_custom
 ROOM_NUMBER="$1"
 COLOR="$2"
 
 ROOM_COUNT=3
+DFAULT_LIGHT_STATE=0
 STATE_0="a\x00\x03\x00\x00\x00|000000000000000000;\
 	000000000000000000;\
 	000000000000000000"
@@ -67,10 +69,14 @@ fi
 
 touch "${TMPFILE_BASE}_$ROOM_NUMBER"
 LIGHT_STATE=$(cat "${TMPFILE_BASE}_$ROOM_NUMBER")
-[ -z "$LIGHT_STATE" ] && LIGHT_STATE=0
+[ -z "$LIGHT_STATE" ] && LIGHT_STATE=$DFAULT_LIGHT_STATE
 
 if [ -z "$COLOR" ]; then
-	LIGHT_STATE=$(( $LIGHT_STATE+1 ))
+	if ! [ -f "${TMPFILE_CUSTOM_BASE}_$ROOM_NUMBER" ]; then		# restore previous colour
+		LIGHT_STATE=$(( $LIGHT_STATE+1 ))
+	else
+		rm -f "${TMPFILE_CUSTOM_BASE}_$ROOM_NUMBER"
+	fi
 	case $LIGHT_STATE in
 		0)
 		  STATE=$STATE_0
@@ -88,6 +94,7 @@ if [ -z "$COLOR" ]; then
 	esac
 else
 	STATE="$(get_room_color_string)"
+	touch "${TMPFILE_CUSTOM_BASE}_$ROOM_NUMBER"
 fi
 
 for i in {1..5}; do