diff --git a/libsrc/atari/rwcommon.s b/libsrc/atari/rwcommon.s
index 6775d9950..d1952f074 100644
--- a/libsrc/atari/rwcommon.s
+++ b/libsrc/atari/rwcommon.s
@@ -5,44 +5,44 @@
 	.include "atari.inc"
 	.include "errno.inc"
 	.importzp tmp2,tmp3
-	.import incsp4,ldax0sp,ldaxysp
+	.import popax
 	.import __errno,__oserror
 	.import	fdtoiocb
 
 	.export __rwsetup
 
+
 __rwsetup:
 
-	sta	tmp2
-	stx	tmp3		; remember size
-	ldy	#3
-	jsr	ldaxysp		; get fd
+	pha			; push size in stack
+	txa
+	pha
+	jsr	popax		; get buffer address
+	pha
+	txa
+	pha
+	jsr	popax		; get handle
 	jsr	fdtoiocb	; convert to iocb
-	bmi	iocberr
+	bmi	iocberr		; negative (X=$FF or A>$7F) on error.
 	tax
-	cpx	#$80		; iocb must be 0...7
-	bcs	iocberr
-	lda	tmp2
-	sta	ICBLL,x
-	lda	tmp3		; size hi
-	sta	ICBLH,x
-	stx	tmp3
-	jsr	ldax0sp		; get buf addr
-	stx	tmp2
-	ldx	tmp3
-	sta	ICBAL,x
-	lda	tmp2
+	pla			; store address
 	sta	ICBAH,x
-	jsr	incsp4		; pop args
-	lda	ICBLL,x
-	ora	ICBLH,x		; return with Z if length was 0
+	pla
+	sta	ICBAL,x
+	pla			; store length
+	sta	ICBLH,x
+	pla
+	sta	ICBLL,x
+	ora	ICBLH,x		; returns Z if length is 0
 	rts
 
-iocberr:jsr	incsp4		; pop args
+iocberr:pla
+	pla
+	pla
+	pla
 	ldx	#$FF		; indicate error + clear ZF
 	rts
 
-
 ;
 ; this routine updates errno.  do a JMP here right after calling
 ; CIOV.	 we expect status in Y.