Index: head/sys/kern/tty.c
===================================================================
--- head/sys/kern/tty.c
+++ head/sys/kern/tty.c
@@ -33,6 +33,7 @@
 __FBSDID("$FreeBSD$");
 
 #include "opt_capsicum.h"
+#include "opt_printf.h"
 
 #include <sys/param.h>
 #include <sys/capsicum.h>
@@ -106,6 +107,12 @@
 
 #define	TTYBUF_MAX	65536
 
+#ifdef PRINTF_BUFR_SIZE
+#define	TTY_PRBUF_SIZE	PRINTF_BUFR_SIZE
+#else
+#define	TTY_PRBUF_SIZE	256
+#endif
+
 /*
  * Allocate buffer space if necessary, and set low watermarks, based on speed.
  * Note that the ttyxxxq_setsize() functions may drop and then reacquire the tty
@@ -1051,7 +1058,9 @@
 	PATCH_FUNC(busy);
 #undef PATCH_FUNC
 
-	tp = malloc(sizeof(struct tty), M_TTY, M_WAITOK|M_ZERO);
+	tp = malloc(sizeof(struct tty) + TTY_PRBUF_SIZE, M_TTY,
+	    M_WAITOK | M_ZERO);
+	tp->t_prbufsz = TTY_PRBUF_SIZE;
 	tp->t_devsw = tsw;
 	tp->t_devswsoftc = sc;
 	tp->t_flags = tsw->tsw_flags;
Index: head/sys/kern/tty_info.c
===================================================================
--- head/sys/kern/tty_info.c
+++ head/sys/kern/tty_info.c
@@ -271,7 +271,7 @@
 	if (tty_checkoutq(tp) == 0)
 		return;
 
-	(void)sbuf_new(&sb, tp->t_prbuf, sizeof(tp->t_prbuf), SBUF_FIXEDLEN);
+	(void)sbuf_new(&sb, tp->t_prbuf, tp->t_prbufsz, SBUF_FIXEDLEN);
 	sbuf_set_drain(&sb, sbuf_tty_drain, tp);
 
 	/* Print load average. */
Index: head/sys/sys/tty.h
===================================================================
--- head/sys/sys/tty.h
+++ head/sys/sys/tty.h
@@ -133,12 +133,8 @@
 	void		*t_hooksoftc;	/* (t) Soft config, for hooks. */
 	struct cdev	*t_dev;		/* (c) Primary character device. */
 
-#ifndef PRINTF_BUFR_SIZE
-#define TTY_PRINTF_SIZE 256
-#else
-#define TTY_PRINTF_SIZE PRINTF_BUFR_SIZE
-#endif
-	char		t_prbuf[TTY_PRINTF_SIZE]; /* (t) */
+	size_t		t_prbufsz;	/* (t) SIGINFO buffer size. */
+	char		t_prbuf[];	/* (t) SIGINFO buffer. */
 };
 
 /*