diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
index 6259730237..b306667230 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
@@ -52,6 +52,11 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 		};
 
 		[CoreConstructor("GEN")]
+		public GPGX(CoreComm comm, byte[] rom, object Settings, object SyncSettings)
+			:this(comm, rom, null, Settings, SyncSettings)
+		{
+		}
+
 		public GPGX(CoreComm comm, byte[] rom, DiscSystem.Disc CD, object Settings, object SyncSettings)
 		{
 			// this can influence some things internally
diff --git a/BizHawk.Emulation.Cores/CoreInventory.cs b/BizHawk.Emulation.Cores/CoreInventory.cs
index cbe34389b1..0b8099a918 100644
--- a/BizHawk.Emulation.Cores/CoreInventory.cs
+++ b/BizHawk.Emulation.Cores/CoreInventory.cs
@@ -60,7 +60,6 @@ namespace BizHawk.Emulation.Cores
 				CoreComm comm,
 				GameInfo game,
 				byte[] rom,
-				Disc cd,
 				bool deterministic,
 				object settings,
 				object syncsettings
@@ -70,7 +69,6 @@ namespace BizHawk.Emulation.Cores
 				bp(o, "comm", comm);
 				bp(o, "game", game);
 				bp(o, "rom", rom);
-				bp(o, "cd", cd);
 				bp(o, "deterministic", deterministic);
 				bp(o, "settings", settings);
 				bp(o, "syncsettings", syncsettings);