diff --git a/src/emu/sound/nes_defs.h b/src/emu/sound/nes_defs.h
index 370fc20c2e7..9890d8efb2a 100644
--- a/src/emu/sound/nes_defs.h
+++ b/src/emu/sound/nes_defs.h
@@ -231,7 +231,7 @@ struct apu_t
 	dpcm_t     dpcm;
 
 	/* APU registers */
-	unsigned char regs[0x17];
+	unsigned char regs[0x18];
 
 	/* Sound pointers */
 	void *buffer;