diff --git a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.ISettable.cs b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.ISettable.cs
index f8420f8c55..80f41eaf43 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.ISettable.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.ISettable.cs
@@ -141,7 +141,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.NDS
 			public string FirmwareUsername
 			{
 				get => _firmwareusername;
-				set => _firmwareusername = value.Substring(0, Math.Min(10, value.Length));
+				set => _firmwareusername = value.Length != 0 ? value.Substring(0, Math.Min(10, value.Length)) : _firmwareusername.Substring(0, 1);
 			}
 
 			public enum Language : int
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.cs b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.cs
index e23066205f..762849231c 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Nintendo/NDS/MelonDS.cs
@@ -90,7 +90,7 @@ namespace BizHawk.Emulation.Cores.Consoles.Nintendo.NDS
 			fwSettings.FirmwareBirthdayMonth = _syncSettings.FirmwareBirthdayMonth;
 			fwSettings.FirmwareBirthdayDay = _syncSettings.FirmwareBirthdayDay;
 			fwSettings.FirmwareFavouriteColour = _syncSettings.FirmwareFavouriteColour;
-			var message = Encoding.UTF8.GetBytes(_syncSettings.FirmwareMessage);
+			var message = _syncSettings.FirmwareMessage.Length != 0 ? Encoding.UTF8.GetBytes(_syncSettings.FirmwareMessage) : new byte[1] { 0 };
 			fwSettings.FirmwareMessageLength = message.Length;
 
 			_exe.AddReadonlyFile(roms[0], "game.rom");