diff --git a/libsrc/atari/do_oserr.s b/libsrc/atari/do_oserr.s
index 7782ac868..534ba2e78 100644
--- a/libsrc/atari/do_oserr.s
+++ b/libsrc/atari/do_oserr.s
@@ -1,17 +1,12 @@
 ;
-; __do_oserror updates __oserror.  Do a JMP here right after calling
-; CIOV.	 It will return with AX set to -1 ($FFFF).  It expects the CIO
+; __do_oserror updates __oserror and errno.  Do a JMP here right after
+; calling CIOV. It will return with AX set to -1 ($FFFF).  It expects the CIO
 ; status in Y.
-;
-; __retminus is a routine whitch returns with AX set to -1 ($FFFF).
 ;
 	.include "errno.inc"
 
-	.export __do_oserror, __retminus
+	.export __do_oserror
 
 __do_oserror:
-	sty	__oserror	; save os dependent error code
-__retminus:
-	lda	#$FF
-	tax			; return -1
-	rts
+	tya
+	jmp	__mappederrno
diff --git a/libsrc/atari/graphics.s b/libsrc/atari/graphics.s
index 3b2c07cbd..120865f82 100644
--- a/libsrc/atari/graphics.s
+++ b/libsrc/atari/graphics.s
@@ -44,9 +44,7 @@ parmok:	jsr	findfreeiocb
 	beq	iocbok		; we found one
 
 	lda	#<EMFILE	; "too many open files"
-seterr:	jsr	__seterrno
-	lda	#$FF
-	tax
+seterr:	jsr	__mappederrno	; @@@ probably not correct to set errno here @@@
 	rts			; return -1
 
 ;invmode:ldx	#>EINVAL
diff --git a/libsrc/atari/inviocb.s b/libsrc/atari/inviocb.s
index 67a6a7c42..b7954dd11 100644
--- a/libsrc/atari/inviocb.s
+++ b/libsrc/atari/inviocb.s
@@ -2,11 +2,9 @@
 ; set EINVAL error code and returns -1
 ;
 	.include "errno.inc"
-	.import	__retminus
 
 	.export	__inviocb
 
 __inviocb:
 	lda	#<EINVAL
-	jsr	__seterrno
-	jmp	__retminus	; return -1
+	jmp	__directerrno
diff --git a/libsrc/atari/lseek.s b/libsrc/atari/lseek.s
index ac033004c..244095969 100644
--- a/libsrc/atari/lseek.s
+++ b/libsrc/atari/lseek.s
@@ -21,10 +21,7 @@
 ; seeking not supported, return -1 and ENOSYS errno value
 no_supp:jsr	incsp6
 	lda	#<ENOSYS
-	jsr	__seterrno      ; set __errno, return zero in A
-       	sta	__oserror
-	lda     #$FF
-	tax
+	jsr	__directerrno	; returns with $FFFF in AX
 	sta	sreg
 	sta	sreg+1
 	rts
@@ -93,8 +90,14 @@ end:	ldx	tmp3
 	bpl	l01
 
 ; error returned from CIO
-xxerr:	sty	__oserror
-	bmi	iocberr
+xxerr:	tya
+	pha
+	jsr	incsp6
+	pla
+	jsr	__mappederrno	; returns with $FFFF in AX
+	sta	sreg
+	sta	sreg+1
+	rts
 
 ; check for offset 0, SEEK_CUR (get current position)
 cont:	ldy	#3
diff --git a/libsrc/atari/open.s b/libsrc/atari/open.s
index 927c1953c..73361336f 100644
--- a/libsrc/atari/open.s
+++ b/libsrc/atari/open.s
@@ -16,7 +16,7 @@
 	.import	clriocb
 	.import	fddecusage,newfd
 	.import	findfreeiocb
-	.import	__do_oserror,incsp4
+	.import	incsp4
 	.import	ldaxysp,addysp
 	.import	__oserror
 	.importzp tmp4,tmp2
@@ -38,7 +38,7 @@ parmok:	jsr	findfreeiocb
 	beq	iocbok		; we found one
 
 	lda	#<EMFILE	; "too many open files"
-seterr:	jsr	__seterrno
+seterr:	jsr	__directerrno
 	jsr	incsp4		; clean up stack
 	lda	#$FF
 	tax
@@ -143,7 +143,8 @@ finish:	php
 
 	bpl	ok
 	jsr	fddecusage	; decrement usage counter of fd as open failed
-	jmp	__do_oserror
+	tya			; put error code into A
+	jmp	__mappederrno
 
 ok:	lda	tmp2		; get fd
 	ldx	#0