diff --git a/sys/dev/tc/mfb.c b/sys/dev/tc/mfb.c
index 1044a50737eb..6c6b3ef442b7 100644
--- a/sys/dev/tc/mfb.c
+++ b/sys/dev/tc/mfb.c
@@ -1,4 +1,4 @@
-/* $NetBSD: mfb.c,v 1.58 2012/01/11 21:12:36 macallan Exp $ */
+/* $NetBSD: mfb.c,v 1.59 2013/11/04 16:53:09 christos Exp $ */
 
 /*-
  * Copyright (c) 1998, 1999 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: mfb.c,v 1.58 2012/01/11 21:12:36 macallan Exp $");
+__KERNEL_RCSID(0, "$NetBSD: mfb.c,v 1.59 2013/11/04 16:53:09 christos Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -260,6 +260,7 @@ mfbattach(device_t parent, device_t self, void *aux)
 	/* clear any pending interrupts */
 	*(uint8_t *)((char *)ri->ri_hw + MX_IREQ_OFFSET) = 0;
 	junk = *(uint8_t *)((char *)ri->ri_hw + MX_IREQ_OFFSET);
+	__USE(junk);
 	*(uint8_t *)((char *)ri->ri_hw + MX_IREQ_OFFSET) = 1;
 
 	waa.console = console;
@@ -471,6 +472,7 @@ mfbintr(void *arg)
 
 	base = (void *)sc->sc_ri->ri_hw;
 	junk = *(uint8_t *)(base + MX_IREQ_OFFSET);
+	__USE(junk);
 #if 0
 	*(uint8_t *)(base + MX_IREQ_OFFSET) = 0;
 #endif
diff --git a/sys/dev/tc/px.c b/sys/dev/tc/px.c
index 6ce8e9f40b34..a7b74a52d1fa 100644
--- a/sys/dev/tc/px.c
+++ b/sys/dev/tc/px.c
@@ -1,4 +1,4 @@
-/* 	$NetBSD: px.c,v 1.39 2012/10/27 17:18:38 chs Exp $	*/
+/* 	$NetBSD: px.c,v 1.40 2013/11/04 16:53:09 christos Exp $	*/
 
 /*-
  * Copyright (c) 1999, 2000, 2001 The NetBSD Foundation, Inc.
@@ -34,7 +34,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: px.c,v 1.39 2012/10/27 17:18:38 chs Exp $");
+__KERNEL_RCSID(0, "$NetBSD: px.c,v 1.40 2013/11/04 16:53:09 christos Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -344,6 +344,7 @@ px_pbuf_post(struct stic_info *si, uint32_t *buf)
 			sr->sr_ipdvint = STIC_INT_P_WE;
 			tc_wmb();
 			junk = *poll;
+			__USE(junk);
 			return (0);
 		}
 		DELAY(STAMP_DELAY);
diff --git a/sys/dev/tc/pxg.c b/sys/dev/tc/pxg.c
index 909621bc31f7..9c6e15b1e648 100644
--- a/sys/dev/tc/pxg.c
+++ b/sys/dev/tc/pxg.c
@@ -1,4 +1,4 @@
-/* 	$NetBSD: pxg.c,v 1.34 2012/03/13 18:40:34 elad Exp $	*/
+/* 	$NetBSD: pxg.c,v 1.35 2013/11/04 16:53:09 christos Exp $	*/
 
 /*-
  * Copyright (c) 1999, 2000, 2001 The NetBSD Foundation, Inc.
@@ -35,7 +35,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: pxg.c,v 1.34 2012/03/13 18:40:34 elad Exp $");
+__KERNEL_RCSID(0, "$NetBSD: pxg.c,v 1.35 2013/11/04 16:53:09 christos Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -338,6 +338,7 @@ pxg_pbuf_post(struct stic_info *si, uint32_t *buf)
 			sr->sr_ipdvint = STIC_INT_P_WE;
 			tc_wmb();
 			junk = *poll;
+			__USE(junk);
 			return (0);
 		}
 		DELAY(STAMP_DELAY);