diff --git a/AMNet.Server/DllMain.cs b/AMNet.Server/DllMain.cs
index 248ded4..c20096d 100644
--- a/AMNet.Server/DllMain.cs
+++ b/AMNet.Server/DllMain.cs
@@ -111,7 +111,7 @@ public static class DllMain
     }
 
     [UnmanagedCallersOnly(EntryPoint = "aime_io_nfc_get_felica_id")]
-    public static int GetFelicaId(byte unitNo, IntPtr idm)
+    public static unsafe int GetFelicaId(byte unitNo, ulong* idm)
     {
         if (!Config.PhysicalCardUseIDm || unitNo != 0)
         {
@@ -123,8 +123,14 @@ public static class DllMain
         {
             return 1;
         }
-     
-        Marshal.Copy(card.IDm, 0, idm, sizeof(ulong));
+
+        ulong idmValue = 0;
+        for (var i = 0 ; i < 8 ; i++) {
+            idmValue = (idmValue << 8) | card.IDm[i];
+        }
+
+        *idm = idmValue;
+
         App.Logger.LogInformation("FeliCa IDm read: {idm}", CardPresenter.FormatHexCode(card.IDm));
         return 0;
     }
diff --git a/readme.md b/readme.md
index 81d176f..f68f7cd 100644
--- a/readme.md
+++ b/readme.md
@@ -38,10 +38,15 @@ This was originally intended for use with maimai and CHUNITHM, but should be com
 
 ### Physical Cards
 AMNet 1.3 adds support for scanning physical cards on iOS devices. If you own a physical AiMe/Banapass/e-Amusement/Suica card, you can scan it using the app and use it in-game.
-By changing the `useAimeDBForPhysicalCards` in segatools.ini, it is also possible to adjust the format of card numbers sent to the game:
+By changing the `useAimeDBForPhysicalCards` in segatools.ini, you can choose how the card is read on a per-game basis:
 
-- `0` - Default value, will send the 20-digit access code on the back of the card to the game and load the save data directly.
-- `1` - Send the card's IDm data to the game, and it will use the connected AiMeDB to retrieve a 20 digit code assigned to the card. This option should be used on shared networks to enable the same account data/profile as you would get on a physical cab.
+- `0` will send the 20-digit access code on the back of the card to the game and load the save data directly (default option).
+- `1` - Send the card's IDm to the game and use AiMeDB to retrieve the 20-digit code assigned to the card.
+
+Mode `1` makes the app function in the same way to a real card reader and should be used if you want the same access code to show when scanning the card on a cab.
+You should also use this option if you're connecting to a hosted server (AquaNet/rinnet/etc).
+
+Additionally, if `useAimeDBForPhysicalCards` is set to `1` and the game is failing to read the card, make sure an up-to-date version of segatools is being used.
 
 ## Interfaces
 AMNet can be used on most platforms, see below for options available for each platform: