diff --git a/mach/m68k2/libem/dia.s b/mach/m68k2/libem/dia.s
index dd7e6a0c3..5174c6693 100644
--- a/mach/m68k2/libem/dia.s
+++ b/mach/m68k2/libem/dia.s
@@ -23,7 +23,7 @@ del	= 0177
 	blt	1f
 	sub	#1,d0
 	bgt	3b
-	clr.b	(a1)
+	clr.b	(a0)
 2:
 	move.l	d2,-(sp)
 	pea	fmt
diff --git a/mach/m68k4/libem/dia.s b/mach/m68k4/libem/dia.s
index fd06f9c64..94a078f0a 100644
--- a/mach/m68k4/libem/dia.s
+++ b/mach/m68k4/libem/dia.s
@@ -23,7 +23,7 @@ del	= 0177
 	blt	1f
 	sub	#1,d0
 	bgt	3b
-	clr.b	(a1)
+	clr.b	(a0)
 2:
 	move.l	d2,-(sp)
 	pea	fmt