diff --git a/sys/net/if_sl.c b/sys/net/if_sl.c
index fefd6b6fb72..fb395740b9f 100644
--- a/sys/net/if_sl.c
+++ b/sys/net/if_sl.c
@@ -628,7 +628,7 @@ sltstart(struct tty *tp)
 		 * output queue.  We are being called in lieu of ttstart
 		 * and must do what it would.
 		 */
-		(*tp->t_oproc)(tp);
+		tt_oproc(tp);
 
 		if (tp->t_outq.c_cc != 0) {
 			if (sc != NULL)
@@ -1110,7 +1110,7 @@ sl_outfill(void *chan)
 			s = splimp ();
 			++SL2IFP(sc)->if_obytes;
 			(void) putc(FRAME_END, &tp->t_outq);
-			(*tp->t_oproc)(tp);
+			tt_oproc(tp);
 			splx (s);
 		} else
 			sc->sc_flags |= SC_OUTWAIT;
diff --git a/sys/net/ppp_tty.c b/sys/net/ppp_tty.c
index 88a73188462..609c58a9d43 100644
--- a/sys/net/ppp_tty.c
+++ b/sys/net/ppp_tty.c
@@ -735,8 +735,7 @@ pppstart(tp)
      * Call output process whether or not there is any output.
      * We are being called in lieu of ttstart and must do what it would.
      */
-    if (tp->t_oproc != NULL)
-	(*tp->t_oproc)(tp);
+    tt_oproc(tp);
 
     /*
      * If the transmit queue has drained and the tty has not hung up
@@ -844,14 +843,13 @@ pppinput(c, tp)
 	if (c == tp->t_cc[VSTOP] && tp->t_cc[VSTOP] != _POSIX_VDISABLE) {
 	    if ((tp->t_state & TS_TTSTOP) == 0) {
 		tp->t_state |= TS_TTSTOP;
-		tp->t_stop(tp, 0);
+		tt_stop(tp, 0);
 	    }
 	    return 0;
 	}
 	if (c == tp->t_cc[VSTART] && tp->t_cc[VSTART] != _POSIX_VDISABLE) {
 	    tp->t_state &= ~TS_TTSTOP;
-	    if (tp->t_oproc != NULL)
-		(*tp->t_oproc)(tp);
+	    tt_oproc(tp);
 	    return 0;
 	}
     }
diff --git a/sys/netgraph/bluetooth/drivers/h4/ng_h4.c b/sys/netgraph/bluetooth/drivers/h4/ng_h4.c
index b84244fe7e9..0aaf37f7301 100644
--- a/sys/netgraph/bluetooth/drivers/h4/ng_h4.c
+++ b/sys/netgraph/bluetooth/drivers/h4/ng_h4.c
@@ -613,8 +613,7 @@ ng_h4_start2(node_p node, hook_p hook, void *arg1, int arg2)
 	 * being called in lieu of ttstart and must do what it would.
 	 */
 
-	if (sc->tp->t_oproc != NULL)
-		(*sc->tp->t_oproc)(sc->tp);
+	tt_oproc(sc->tp);
 
 	/*
 	 * This timeout is needed for operation on a pseudo-tty, because the
diff --git a/sys/netgraph/ng_tty.c b/sys/netgraph/ng_tty.c
index 380bcdf6b55..7b8eceb789e 100644
--- a/sys/netgraph/ng_tty.c
+++ b/sys/netgraph/ng_tty.c
@@ -445,8 +445,7 @@ ngt_start(struct tty *tp)
 
 	/* Call output process whether or not there is any output. We are
 	 * being called in lieu of ttstart and must do what it would. */
-	if (tp->t_oproc != NULL)
-		(*tp->t_oproc) (tp);
+	tt_oproc(tp);
 
 	/* This timeout is needed for operation on a pseudo-tty, because the
 	 * pty code doesn't call pppstart after it has drained the t_outq. */