diff --git a/src/emu/machine/corvushd.h b/src/emu/machine/corvushd.h
index b3d1f6a5bbf..9deaa7315f3 100644
--- a/src/emu/machine/corvushd.h
+++ b/src/emu/machine/corvushd.h
@@ -356,7 +356,7 @@ private:
 		//
 		struct {
 			UINT8   status;                     // Status code returned by command executed
-			UINT8   firmware[33];               // Firmware message
+			UINT8   firmware[32];               // Firmware message
 			UINT8   rom_version;                // ROM Version
 			struct {
 				UINT8   sectors_per_track;      // Sectors/Track