diff --git a/quest_api.lua b/quest_api.lua
index c985478..8d92e2c 100644
--- a/quest_api.lua
+++ b/quest_api.lua
@@ -441,8 +441,11 @@ yl_speak_up.get_fs_manage_variables = function(player, param)
 		if(k_long
 		  and yl_speak_up.player_vars[ k_long ]
 		  and yl_speak_up.player_vars[ k_long ][ "$META$"]) then
-			for key, v in pairs(yl_speak_up.player_vars[ k_long ][ "$META$"][
-							"used_by_npc" ] or {}) do
+			local t = yl_speak_up.player_vars[ k_long ][ "$META$"]["used_by_npc" ]
+			if(type(t) ~= "table") then
+				t = {}
+			end
+			for key, v in pairs(t or {}) do
 				if(c1==0) then
 					list_of_npc_users = minetest.formspec_escape(key)
 				else
@@ -451,8 +454,11 @@ yl_speak_up.get_fs_manage_variables = function(player, param)
 				end
 				c1 = c1 + 1
 			end
-			for key, v in pairs(yl_speak_up.player_vars[ k_long ][ "$META$" ][
-							"used_by_node_pos" ] or {}) do
+			local t = yl_speak_up.player_vars[ k_long ][ "$META$"]["used_by_node_pos" ]
+			if(type(t) ~= "table") then
+				t = {}
+			end
+			for key, v in pairs(t or {}) do
 				if(c2==0) then
 					list_of_node_pos_users = minetest.formspec_escape(key)
 				else
@@ -734,6 +740,18 @@ yl_speak_up.update_stored_npc_data = function(n_id, dialog)
 		last_modified = os.date(),
 	}
 
+	-- make sure all variables have a metadata field
+	for k, v in pairs(yl_speak_up.player_vars) do
+		if(   yl_speak_up.player_vars[ k ][ "$META$" ]
+		  and yl_speak_up.player_vars[ k ][ "$META$" ].used_by_npc) then
+			if(type(yl_speak_up.player_vars[ k ][ "$META$" ].used_by_npc) ~= "table") then
+				yl_speak_up.player_vars[ k ][ "$META$" ].used_by_npc = {}
+			end
+			-- delete old entries (the correct new ones will be set shortly after this)
+			yl_speak_up.player_vars[ k ][ "$META$"].used_by_npc[ n_id ] = nil
+		end
+	end
+
 	-- save in the variables' metadata which NPC uses it
 	-- (this is what we're mostly after - know which variable is used in which NPC)
 	for k, v in pairs(variables_p) do