diff --git a/FactorioClient.py b/FactorioClient.py
index ce5cee54..9babdc72 100644
--- a/FactorioClient.py
+++ b/FactorioClient.py
@@ -198,7 +198,7 @@ async def factorio_server_watcher(ctx: FactorioContext):
                     else:
                         item_name = lookup_id_to_name[item_id]
                         factorio_server_logger.info(f"Sending {item_name} to Nauvis from {player_name}.")
-                        ctx.rcon_client.send_command(f'/ap-get-technology {item_name} {player_name}')
+                        ctx.rcon_client.send_command(f'/ap-get-technology {item_name}\t{ctx.send_index}\t{player_name}')
                     ctx.send_index += 1
             await asyncio.sleep(0.1)
 
diff --git a/data/factorio/mod/lib.lua b/data/factorio/mod/lib.lua
index 2d77bc95..a341effe 100644
--- a/data/factorio/mod/lib.lua
+++ b/data/factorio/mod/lib.lua
@@ -20,4 +20,16 @@ function get_any_stack_size(name)
     end
     -- failsafe
     return 1
+end
+
+-- from https://stackoverflow.com/a/40180465
+-- split("a,b,c", ",") => {"a", "b", "c"}
+function split(s, sep)
+    local fields = {}
+
+    sep = sep or " "
+    local pattern = string.format("([^%s]+)", sep)
+    string.gsub(s, pattern, function(c) fields[#fields + 1] = c end)
+
+    return fields
 end
\ No newline at end of file
diff --git a/data/factorio/mod_template/control.lua b/data/factorio/mod_template/control.lua
index 56536be0..f83f04e0 100644
--- a/data/factorio/mod_template/control.lua
+++ b/data/factorio/mod_template/control.lua
@@ -220,14 +220,20 @@ end)
 
 commands.add_command("ap-get-technology", "Grant a technology, used by the Archipelago Client.", function(call)
     local force = game.forces["player"]
-    chunks = {}
-    for substring in call.parameter:gmatch("%S+") do -- split on " "
-        table.insert(chunks, substring)
-    end
+    chunks = split(call.parameter, "\t")
     local tech_name = chunks[1]
-    local source = chunks[2] or "Archipelago"
+    local index = chunks[2]
+    local source = chunks[3] or "Archipelago"
     local tech = force.technologies[tech_name]
+
     if tech ~= nil then
+        if global.index_sync == nil then
+            global.index_sync = {}
+        end
+        if global.index_sync[index] ~= nil and global.index_sync[index] ~= tech then
+            game.print("Warning: Desync Detected. Duplicate/Missing items may occur.")
+        end
+        global.index_sync[index] = tech
         if tech.researched ~= true then
             game.print({"", "Received [technology=" .. tech.name .. "] from ", source})
             game.play_sound({path="utility/research_completed"})