diff --git a/posix-power/Makefile b/posix-power/Makefile
index d106fa7..75c8ca8 100644
--- a/posix-power/Makefile
+++ b/posix-power/Makefile
@@ -2,7 +2,7 @@ ROOT=..
 include ../Make.config
 LIB=../libmachdep.a
 
-CFLAGS+= -Wa,-mregnames
+#CFLAGS+= -Wa,-mregnames
 
 OFILES=\
 	getcallerpc.$O\
diff --git a/posix-power/tas.c b/posix-power/tas.c
index 7f9e5c0..4e52aef 100644
--- a/posix-power/tas.c
+++ b/posix-power/tas.c
@@ -15,16 +15,16 @@ tas(int *x)
 	 * r4 (x) and r5 (temp).
 	 */
 	__asm__("\n	sync\n"
-	"	li	r0,0\n"
-	"	mr	r4,%1		/* &l->val */\n"
-	"	lis	r5,0xdead	/* assemble constant 0xdeaddead */\n"
-	"	ori	r5,r5,0xdead	/* \" */\n"
+	"	li	%%r0,0\n"
+	"	mr	%%r4,%1		/* &l->val */\n"
+	"	lis	%%r5,0xdead	/* assemble constant 0xdeaddead */\n"
+	"	ori	%%r5,%%r5,0xdead	/* \" */\n"
 	"tas1:\n"
-	"	dcbf	r4,r0	/* cache flush; \"fix for 603x bug\" */\n"
-	"	lwarx	%0,r4,r0	/* v = l->val with reservation */\n"
-	"	cmp	cr0,0,%0,r0	/* v == 0 */\n"
+	"	dcbf	%%r4,%%r0	/* cache flush; \"fix for 603x bug\" */\n"
+	"	lwarx	%0,%%r4,%%r0	/* v = l->val with reservation */\n"
+	"	cmp	cr0,0,%0,%%r0	/* v == 0 */\n"
 	"	bne	tas0\n"
-	"	stwcx.	r5,r4,r0   /* if (l->val same) l->val = 0xdeaddead */\n"
+	"	stwcx.	%%r5,%%r4,%%r0   /* if (l->val same) l->val = 0xdeaddead */\n"
 	"	bne	tas1\n"
 	"tas0:\n"
 	"	sync\n"