diff --git a/BizHawk.Emulation.Cores/Consoles/PC Engine/CDLMapping.cs b/BizHawk.Emulation.Cores/Consoles/PC Engine/CDLMapping.cs
index 316848af2d..0bb2b2d864 100644
--- a/BizHawk.Emulation.Cores/Consoles/PC Engine/CDLMapping.cs	
+++ b/BizHawk.Emulation.Cores/Consoles/PC Engine/CDLMapping.cs	
@@ -47,6 +47,7 @@ namespace BizHawk.Emulation.Cores.PCEngine
 				{
 					// mark as unknown mirrors
 					mm[i].Name = null;
+					mm[i].Offs = 0;
 				}
 				for (int i = 0x40; i < 0x50; i++)
 				{