diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/TVROM.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/TVROM.cs
index d95a108c5d..e4f25e2bb2 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/TVROM.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/TVROM.cs
@@ -8,6 +8,13 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			//analyze board type
 			switch (Cart.board_type)
 			{
+				case "MAPPER004":
+					if (Cart.inesmirroring != 2) // send these to TxROM
+						return false;
+					Cart.vram_size = 8;
+					break;
+
+
 				case "NES-TVROM": //rad racer II (U)
 					AssertPrg(64); AssertChr(64); AssertVram(8); AssertWram(0);
 					AssertBattery(false);
diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/TxROM.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/TxROM.cs
index d197102fe7..a585a2d48c 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/TxROM.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/Boards/MMC3_family/TxROM.cs
@@ -40,7 +40,10 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 					break;
 
 				case "TXROM-HOMEBREW": // should this even exist?
+					break;
 				case "MAPPER004":
+					if (Cart.inesmirroring == 2) // send these to TVROM
+						return false;
 					break;
 				case "NES-TBROM": //tecmo world cup soccer (DE) [untested]
 				case "HVC-TBROM":