diff --git a/src/BizHawk.Emulation.Cores/Consoles/NEC/PCFX/Tst.cs b/src/BizHawk.Emulation.Cores/Consoles/NEC/PCFX/Tst.cs
index 1a5fe45124..16187dd332 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/NEC/PCFX/Tst.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/NEC/PCFX/Tst.cs
@@ -20,6 +20,8 @@ namespace BizHawk.Emulation.Cores.Consoles.NEC.PCFX
 		public Tst(CoreLoadParameters<NymaSettings, NymaSyncSettings> lp)
 			: base(lp.Comm, "PCFX", "PC-FX Controller", lp.Settings, lp.SyncSettings)
 		{
+			if (lp.Roms.Count > 0)
+				throw new InvalidOperationException("To load a PC-FX game, please load the CUE file and not the BIN file.");
 			var firmwares = new Dictionary<string, (string, string)>
 			{
 				{ "FIRMWARE:pcfx.rom", ("PCFX", "BIOS") },
diff --git a/src/BizHawk.Emulation.Cores/Consoles/Sega/Saturn/Saturnus.cs b/src/BizHawk.Emulation.Cores/Consoles/Sega/Saturn/Saturnus.cs
index 7b7b81ec0f..de6e65d756 100644
--- a/src/BizHawk.Emulation.Cores/Consoles/Sega/Saturn/Saturnus.cs
+++ b/src/BizHawk.Emulation.Cores/Consoles/Sega/Saturn/Saturnus.cs
@@ -29,6 +29,8 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.Saturn
 		public Saturnus(CoreLoadParameters<NymaSettings, NymaSyncSettings> lp)
 			: base(lp.Comm, "SAT", "Saturn Controller", lp.Settings, lp.SyncSettings)
 		{
+			if (lp.Roms.Count > 0)
+				throw new InvalidOperationException("To load a Saturn game, please load the CUE file and not the BIN file.");
 			var firmwares = new Dictionary<string, (string, string)>
 			{
 				{ "FIRMWARE:$J", ("SAT", "J") },