diff --git a/Source/HBIOS/hbios.asm b/Source/HBIOS/hbios.asm
index 30bb4887..0cbbf3c4 100644
--- a/Source/HBIOS/hbios.asm
+++ b/Source/HBIOS/hbios.asm
@@ -359,6 +359,7 @@ RTCDEF	.SET	RTCDEF | %00001000	; INITIAL SPEED LOW
   #DEFINE EZ80_BNKSEL 	.DB	$49, $DF	; RST.L $18
 
   #DEFINE RET.L		.DB	$49 \ RET
+IO_SEGMENT	.EQU		$FF		; THE UPPER 8-BIT ADDRESS FOR I/O
 
 #ELSE
   #DEFINE EZ80_IO
diff --git a/Source/HBIOS/tms.asm b/Source/HBIOS/tms.asm
index 8c776315..fd955b16 100644
--- a/Source/HBIOS/tms.asm
+++ b/Source/HBIOS/tms.asm
@@ -1100,8 +1100,12 @@ TMS_Z180IOX:
 
 #IF (TMSTIMENABLE & (INTMODE > 0))
 TMS_TSTINT:
-	EZ80_IO
+#IF (CPUFAM == CPU_EZ80)
+	LD	BC, IO_SEGMENT<<8 | TMS_CMDREG
+	IN	A,(C)			; TEST FOR INT FLAG
+#ELSE
 	IN	A,(TMS_CMDREG)		; TEST FOR INT FLAG
+#ENDIF
 	AND	$80
 	JR	NZ,TMS_INTHNDL
 	AND	$00			; RETURN Z - NOT HANDLED