diff --git a/digilines_lcd/init.lua b/digilines_lcd/init.lua
index fa02197..3d98e1c 100644
--- a/digilines_lcd/init.lua
+++ b/digilines_lcd/init.lua
@@ -105,7 +105,9 @@ minetest.register_node("digilines_lcd:lcd", {
 	end,
 
 	on_receive_fields = function(pos, formname, fields, sender)
-		minetest.get_meta(pos):set_string("channel", fields.channel)
+		if (fields.channel) then
+			minetest.get_meta(pos):set_string("channel", fields.channel)
+		end
 	end,
 
 	digiline = 
diff --git a/digilines_lightsensor/init.lua b/digilines_lightsensor/init.lua
index 2bbbc27..7dda1ce 100644
--- a/digilines_lightsensor/init.lua
+++ b/digilines_lightsensor/init.lua
@@ -50,8 +50,8 @@ minetest.register_node("digilines_lightsensor:lightsensor", {
 		meta:set_string("formspec", "field[channel;Channel;${channel}]")
 	end,
 	on_receive_fields = function(pos, formname, fields, sender)
-		local meta = minetest.get_meta(pos)
-		fields.channel = fields.channel or ""
-		meta:set_string("channel", fields.channel)
+		if (fields.channel) then
+			minetest.get_meta(pos):set_string("channel", fields.channel)
+		end
 	end,
 })
diff --git a/digilines_rtc/init.lua b/digilines_rtc/init.lua
index 40e84d0..6b7bfaf 100644
--- a/digilines_rtc/init.lua
+++ b/digilines_rtc/init.lua
@@ -46,8 +46,8 @@ minetest.register_node("digilines_rtc:rtc", {
 		meta:set_string("formspec", "field[channel;Channel;${channel}]")
 	end,
 	on_receive_fields = function(pos, formname, fields, sender)
-		local meta = minetest.get_meta(pos)
-		fields.channel = fields.channel or ""
-		meta:set_string("channel", fields.channel)
+		if (fields.channel) then
+			minetest.get_meta(pos):set_string("channel", fields.channel)
+		end
 	end,
 })