diff --git a/Source/HBIOS/sio.asm b/Source/HBIOS/sio.asm
index cb3cb2eb..ade6e588 100644
--- a/Source/HBIOS/sio.asm
+++ b/Source/HBIOS/sio.asm
@@ -970,7 +970,11 @@ BROK:
 SIO_INITVALS:
 	.DB	$00, $18		; WR0: CHANNEL RESET
 	.DB	$04, $00		; WR4: CLK BAUD PARITY STOP BIT ; PST
+#IF (INTMODE == 0)
+	.DB	$01, $00		; WR1: NO INTERRUPTS
+#ELSE
 	.DB	$01, $18		; WR1: INTERRUPT ON ALL RECEIVE CHARACTERS
+#ENDIF
 	.DB	$02, IVT_SER0		; WR2: INTERRUPT VECTOR OFFSET
 	.DB	$03, $C1		; WR3: 8 BIT RCV, RX ENABLE
 	.DB	$05, $EA		; WR5: DTR, 8 BITS SEND,  TX ENABLE, RTS 1 11 0 1 0 1 0 (1=DTR,11=8bits,0=sendbreak,1=TxEnable,0=sdlc,1=RTS,0=txcrc)