diff --git a/BizHawk.Emulation.Cores/CPUs/CP1610/CP1610.cs b/BizHawk.Emulation.Cores/CPUs/CP1610/CP1610.cs
index 53dd4cee52..70605cc81e 100644
--- a/BizHawk.Emulation.Cores/CPUs/CP1610/CP1610.cs
+++ b/BizHawk.Emulation.Cores/CPUs/CP1610/CP1610.cs
@@ -82,7 +82,7 @@ namespace BizHawk.Emulation.Cores.Components.CP1610
 			ser.Sync(nameof(IntRM), ref IntRM);
 			ser.Sync(nameof(BusRq), ref BusRq);
 			ser.Sync(nameof(BusAk), ref BusAk);
-			ser.Sync(nameof(BusRq), ref BusRq);
+			ser.Sync("Duplicate_Bus_Rq", ref BusRq); // Can't remove this or it will break backward compatibility with binary states
 			ser.Sync(nameof(Interruptible), ref Interruptible);
 			ser.Sync(nameof(Interrupted), ref Interrupted);
 			ser.Sync("Toal_executed_cycles", ref TotalExecutedCycles);