diff --git a/mach/m68k4/libem/inn.s b/mach/m68k4/libem/inn.s
index ef0176274..6c449bb93 100644
--- a/mach/m68k4/libem/inn.s
+++ b/mach/m68k4/libem/inn.s
@@ -1,34 +1,32 @@
-.define .inn
+.define	.inn
 .sect .text
 .sect .rom
 .sect .data
 .sect .bss
+.sect .text
 
-! d0 : set size in bytes
-! d1 : bitnumber
+.inn:	! d0 bitnumber
+	! d1 setsize in bytes
+	! on exit: 0 or 1 in d0
 
-	.sect .text
-.inn:
-	move.l	(sp)+,a1
-	move.l	(sp)+,d1
-	move.l	d0,-(sp)
-	move.l	sp,a0
-	add.l	#4,a0
-	move.l	d1,d2
-	asr.l	#3,d2
-	cmp.l	d0,d2
-	bcc	1f
-	bclr	#0,d2
-	bclr	#1,d2
-	add.l	d2,a0
-	move.l	(a0),d2
-	btst	d1,d2
-	beq	1f
-	move.l	#1,d0
-	bra	2f
+	move.l	d2, -(sp)
+	move.l	d0, d2
+	asr.l	#3, d2		! offset .sect from sp in bytes
+	eor.l	#3, d2		! longs are stored in high-to-low order
+	cmp.l	d1, d2
+	bge	1f		! bitnumber too large
+	btst	d0, 8(sp, d2.l)
+	beq	2f
+	move.l	#1, d0
+	bra	3f
 1:
-	clr.l	d0
+	move.l	#ESET, -(sp)
+	jsr	.trp
 2:
-	move.l	(sp)+,d1
-	add.l	d1,sp
-	jmp	(a1)
+	clr.l	d0
+3:
+	move.l	(sp)+, d2
+	move.l	(sp)+, a0	! return address
+	add.l	d1, sp		! pop bitset
+	jmp	(a0)		! return
+.align 2