diff --git a/src/mame/drivers/segas16b.c b/src/mame/drivers/segas16b.c
index 292eb39f3b6..7a3d27845a1 100644
--- a/src/mame/drivers/segas16b.c
+++ b/src/mame/drivers/segas16b.c
@@ -6840,7 +6840,7 @@ static WRITE16_HANDLER( isgsm_data_w )
 
 		for (int i=0;i<bytes_to_write;i++)
 		{
-			UINT8 byte;
+			UINT8 byte=0;
 
 			if (isgsm_mode&0x8)
 			{