diff --git a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/BoardSystem.cs b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/BoardSystem.cs
index e0b21fa53b..94ecce0845 100644
--- a/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/BoardSystem.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Nintendo/NES/BoardSystem.cs
@@ -187,7 +187,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.NES
 			public virtual void WriteWRAM(int addr, byte value)
 			{
 				if(wram != null)
-					wram[addr] = value;
+					wram[addr & wram_mask] = value;
 			}
 
 			private int wram_mask;