diff --git a/functions.lua b/functions.lua
index e8b6e97..0900b2a 100644
--- a/functions.lua
+++ b/functions.lua
@@ -1855,8 +1855,8 @@ minetest.register_on_player_receive_fields(
 
 -- helper function
 yl_speak_up.add_new_dialog = function(dialog, pname)
-	next_id = find_next_id(dialog.n_dialogs)
-	future_d_id = "d_" .. next_id
+	local next_id = find_next_id(dialog.n_dialogs)
+	local future_d_id = "d_" .. next_id
 	-- Initialize empty dialog
 	dialog.n_dialogs[future_d_id] = {
 		d_id = future_d_id,