diff --git a/sys/amd64/amd64/machdep.c b/sys/amd64/amd64/machdep.c
index 1ea73604ffa..2e6416745bb 100644
--- a/sys/amd64/amd64/machdep.c
+++ b/sys/amd64/amd64/machdep.c
@@ -400,7 +400,7 @@ again:
 	 */
 	SLIST_INIT(&callfree);
 	for (i = 0; i < ncallout; i++) {
-		callout_init(&callout[i]);
+		callout_init(&callout[i], 0);
 		callout[i].c_flags = CALLOUT_LOCAL_ALLOC;
 		SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle);
 	}
diff --git a/sys/i386/i386/machdep.c b/sys/i386/i386/machdep.c
index 1ea73604ffa..2e6416745bb 100644
--- a/sys/i386/i386/machdep.c
+++ b/sys/i386/i386/machdep.c
@@ -400,7 +400,7 @@ again:
 	 */
 	SLIST_INIT(&callfree);
 	for (i = 0; i < ncallout; i++) {
-		callout_init(&callout[i]);
+		callout_init(&callout[i], 0);
 		callout[i].c_flags = CALLOUT_LOCAL_ALLOC;
 		SLIST_INSERT_HEAD(&callfree, &callout[i], c_links.sle);
 	}
diff --git a/sys/kern/kern_timeout.c b/sys/kern/kern_timeout.c
index 72b5302fd32..5576e0872fc 100644
--- a/sys/kern/kern_timeout.c
+++ b/sys/kern/kern_timeout.c
@@ -173,7 +173,7 @@ struct callout_handle
 timeout(ftn, arg, to_ticks)
 	timeout_t *ftn;
 	void *arg;
-	register int to_ticks;
+	int to_ticks;
 {
 	int s;
 	struct callout *new;
@@ -242,12 +242,11 @@ callout_handle_init(struct callout_handle *handle)
  * callout_deactivate() - marks the callout as having been serviced
  */
 void
-_callout_reset(c, to_ticks, ftn, arg, flags)
+callout_reset(c, to_ticks, ftn, arg)
 	struct	callout *c;
 	int	to_ticks;
 	void	(*ftn) __P((void *));
 	void	*arg;
-	int	flags;
 {
 	int	s;
 
@@ -265,8 +264,7 @@ _callout_reset(c, to_ticks, ftn, arg, flags)
 		to_ticks = 1;
 
 	c->c_arg = arg;
-	c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING |
-	    (flags & CALLOUT_MPSAFE));
+	c->c_flags |= (CALLOUT_ACTIVE | CALLOUT_PENDING);
 	c->c_func = ftn;
 	c->c_time = ticks + to_ticks;
 	TAILQ_INSERT_TAIL(&callwheel[c->c_time & callwheelmask], 
@@ -308,10 +306,13 @@ callout_stop(c)
 }
 
 void
-callout_init(c)
+callout_init(c, mpsafe)
 	struct	callout *c;
+	int mpsafe;
 {
 	bzero(c, sizeof *c);
+	if (mpsafe)
+		c->c_flags |= CALLOUT_MPSAFE;
 }
 
 #ifdef APM_FIXUP_CALLTODO
diff --git a/sys/netinet/tcp_subr.c b/sys/netinet/tcp_subr.c
index c3616a524fa..64302c6e17b 100644
--- a/sys/netinet/tcp_subr.c
+++ b/sys/netinet/tcp_subr.c
@@ -490,11 +490,11 @@ tcp_newtcpcb(inp)
 		tcp_mssdflt;
 
 	/* Set up our timeouts. */
-	callout_init(tp->tt_rexmt = &it->inp_tp_rexmt);
-	callout_init(tp->tt_persist = &it->inp_tp_persist);
-	callout_init(tp->tt_keep = &it->inp_tp_keep);
-	callout_init(tp->tt_2msl = &it->inp_tp_2msl);
-	callout_init(tp->tt_delack = &it->inp_tp_delack);
+	callout_init(tp->tt_rexmt = &it->inp_tp_rexmt, 0);
+	callout_init(tp->tt_persist = &it->inp_tp_persist, 0);
+	callout_init(tp->tt_keep = &it->inp_tp_keep, 0);
+	callout_init(tp->tt_2msl = &it->inp_tp_2msl, 0);
+	callout_init(tp->tt_delack = &it->inp_tp_delack, 0);
 
 	if (tcp_do_rfc1323)
 		tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
diff --git a/sys/netinet/tcp_timewait.c b/sys/netinet/tcp_timewait.c
index c3616a524fa..64302c6e17b 100644
--- a/sys/netinet/tcp_timewait.c
+++ b/sys/netinet/tcp_timewait.c
@@ -490,11 +490,11 @@ tcp_newtcpcb(inp)
 		tcp_mssdflt;
 
 	/* Set up our timeouts. */
-	callout_init(tp->tt_rexmt = &it->inp_tp_rexmt);
-	callout_init(tp->tt_persist = &it->inp_tp_persist);
-	callout_init(tp->tt_keep = &it->inp_tp_keep);
-	callout_init(tp->tt_2msl = &it->inp_tp_2msl);
-	callout_init(tp->tt_delack = &it->inp_tp_delack);
+	callout_init(tp->tt_rexmt = &it->inp_tp_rexmt, 0);
+	callout_init(tp->tt_persist = &it->inp_tp_persist, 0);
+	callout_init(tp->tt_keep = &it->inp_tp_keep, 0);
+	callout_init(tp->tt_2msl = &it->inp_tp_2msl, 0);
+	callout_init(tp->tt_delack = &it->inp_tp_delack, 0);
 
 	if (tcp_do_rfc1323)
 		tp->t_flags = (TF_REQ_SCALE|TF_REQ_TSTMP);
diff --git a/sys/sys/callout.h b/sys/sys/callout.h
index a46055ebea8..9eecb44cde7 100644
--- a/sys/sys/callout.h
+++ b/sys/sys/callout.h
@@ -77,18 +77,11 @@ extern struct mtx callout_lock;
 
 #define	callout_active(c)	((c)->c_flags & CALLOUT_ACTIVE)
 #define	callout_deactivate(c)	((c)->c_flags &= ~CALLOUT_ACTIVE)
-void	callout_init __P((struct callout *));
+void	callout_init __P((struct callout *, int));
 #define	callout_pending(c)	((c)->c_flags & CALLOUT_PENDING)
-void	_callout_reset __P((struct callout *, int, void (*)(void *), void *,
-			    int));
+void	callout_reset __P((struct callout *, int, void (*)(void *), void *));
 void	callout_stop __P((struct callout *));
 
-#define	callout_reset(c, ticks, func, arg)				\
-	_callout_reset((c), (ticks), (func), (arg), 0)
-
-#define	mp_callout_reset(c, ticks, func, arg)				\
-	_callout_reset((c), (ticks), (func), (arg), CALLOUT_MPSAFE)
-
 #endif
 
 #endif /* _SYS_CALLOUT_H_ */