diff --git a/UPDATING b/UPDATING
index 98b8d95b93c6..fe27b4f87954 100644
--- a/UPDATING
+++ b/UPDATING
@@ -37,7 +37,9 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 9.x IS SLOW:
 
 	After the system has been upgraded, it is safe to remove the old
 	log files (/var/run/utmp, /var/log/lastlog and /var/log/wtmp*),
-	assuming their contents is of no importance anymore.
+	assuming their contents is of no importance anymore.  Old wtmp
+	databases can only be used by last(1) and ac(8) after they have
+	been converted to the new format using wtmpcvt(1).
 
 20100108:
 	Introduce the kernel thread "deadlock resolver" (which can be enabled
diff --git a/lib/libc/gen/getutxent.3 b/lib/libc/gen/getutxent.3
index 57887b131728..c37240eb3a14 100644
--- a/lib/libc/gen/getutxent.3
+++ b/lib/libc/gen/getutxent.3
@@ -401,6 +401,7 @@ The file format is invalid.
 .Sh SEE ALSO
 .Xr last 1 ,
 .Xr write 1 ,
+.Xr wtmpcvt 1 ,
 .Xr getpid 2 ,
 .Xr gettimeofday 2 ,
 .Xr tty 4 ,
diff --git a/usr.bin/Makefile b/usr.bin/Makefile
index 9120613d4366..1917ae2a0b56 100644
--- a/usr.bin/Makefile
+++ b/usr.bin/Makefile
@@ -225,6 +225,7 @@ SUBDIR=	alias \
 	who \
 	whois \
 	write \
+	wtmpcvt \
 	xargs \
 	xinstall \
 	${_xlint} \
diff --git a/usr.bin/wtmpcvt/Makefile b/usr.bin/wtmpcvt/Makefile
new file mode 100644
index 000000000000..0caa097be1c8
--- /dev/null
+++ b/usr.bin/wtmpcvt/Makefile
@@ -0,0 +1,5 @@
+# $FreeBSD$
+
+PROG=	wtmpcvt
+
+.include <bsd.prog.mk>
diff --git a/usr.bin/wtmpcvt/wtmpcvt.1 b/usr.bin/wtmpcvt/wtmpcvt.1
new file mode 100644
index 000000000000..7f0ed0823aad
--- /dev/null
+++ b/usr.bin/wtmpcvt/wtmpcvt.1
@@ -0,0 +1,66 @@
+.\" Copyright (c) 2010 Ed Schouten <ed@FreeBSD.org>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd January 14, 2010
+.Os
+.Dt WTMPCVT 1
+.Sh NAME
+.Nm wtmpcvt
+.Nd convert wtmp files to the utmpx format
+.Sh SYNOPSIS
+.Nm
+.Ar input
+.Ar output
+.Sh DESCRIPTION
+The
+.Nm
+utility converts traditional
+.Pa wtmp
+user accounting database files to the same format that is used by
+.Pa /var/log/utx.log .
+This makes it possible to view their contents using existing accouting
+utilities, such as
+.Xr last 1
+and
+.Xr ac 8 .
+.Sh SEE ALSO
+.Xr last 1 ,
+.Xr getutxent 3 ,
+.Xr ac 8
+.Sh HISTORY
+The
+.Nm
+utility appeared in
+.Fx 9.0 .
+.Sh BUGS
+The application assumes the
+.Ar input
+file has the same byte order as the host system.
+The
+.Ar output
+file can be used on any architecture.
+.Sh AUTHORS
+.An Ed Schouten Aq ed@FreeBSD.org
diff --git a/usr.bin/wtmpcvt/wtmpcvt.c b/usr.bin/wtmpcvt/wtmpcvt.c
new file mode 100644
index 000000000000..aa4e25e2c395
--- /dev/null
+++ b/usr.bin/wtmpcvt/wtmpcvt.c
@@ -0,0 +1,138 @@
+/*-
+ * Copyright (c) 2010 Ed Schouten <ed@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/endian.h>
+#include <sys/param.h>
+
+#include <err.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <utmpx.h>
+
+#include "../../lib/libc/gen/utxdb.h"
+
+struct outmp {
+	char	ut_line[8];
+	char	ut_user[16];
+	char	ut_host[16];
+	int32_t	ut_time;
+};
+
+static void
+usage(void)
+{
+
+	fprintf(stderr, "usage: wtmpcvt input output\n");
+	exit(1);
+}
+
+static void
+outmp_to_futx(const struct outmp *ui, struct futx *uo)
+{
+
+	memset(uo, 0, sizeof *uo);
+#define	COPY_STRING(field) do {						\
+	strncpy(uo->fu_ ## field, ui->ut_ ## field,			\
+	    MIN(sizeof uo->fu_ ## field, sizeof ui->ut_ ## field));	\
+} while (0)
+#define	COPY_LINE_TO_ID() do {						\
+	strncpy(uo->fu_id, ui->ut_line,					\
+	    MIN(sizeof uo->fu_id, sizeof ui->ut_line));			\
+} while (0)
+#define	MATCH(field, value)	(strncmp(ui->ut_ ## field, (value),	\
+					sizeof(ui->ut_ ## field)) == 0)
+	if (MATCH(user, "reboot") && MATCH(line, "~"))
+		uo->fu_type = BOOT_TIME;
+	else if (MATCH(user, "date") && MATCH(line, "|"))
+		uo->fu_type = OLD_TIME;
+	else if (MATCH(user, "date") && MATCH(line, "{"))
+		uo->fu_type = NEW_TIME;
+	else if (MATCH(user, "shutdown") && MATCH(line, "~"))
+		uo->fu_type = SHUTDOWN_TIME;
+	else if (MATCH(user, "") && MATCH(host, "") && !MATCH(line, "")) {
+		uo->fu_type = DEAD_PROCESS;
+		COPY_LINE_TO_ID();
+	} else if (!MATCH(user, "") && !MATCH(line, "") && ui->ut_time != 0) {
+		uo->fu_type = USER_PROCESS;
+		COPY_STRING(user);
+		COPY_STRING(line);
+		COPY_STRING(host);
+		COPY_LINE_TO_ID();
+	} else {
+		uo->fu_type = EMPTY;
+		return;
+	}
+#undef COPY_STRING
+#undef COPY_LINE_TO_ID
+#undef MATCH
+
+	/* Timestamp conversion. XXX: Assumes host byte order! */
+	uo->fu_tv = htobe64((uint64_t)ui->ut_time * 1000000);
+}
+
+int
+main(int argc, char *argv[])
+{
+	FILE *in, *out;
+	struct outmp ui;
+	struct futx uo;
+	size_t l;
+	uint16_t lo;
+
+	if (argc != 3)
+		usage();
+
+	/* Open files. */
+	in = fopen(argv[1], "r");
+	if (in == NULL)
+		err(1, argv[1]);
+	out = fopen(argv[2], "w");
+	if (out == NULL)
+		err(1, argv[2]);
+
+	/* Process entries. */
+	while (fread(&ui, sizeof ui, 1, in) == 1) {
+		outmp_to_futx(&ui, &uo);
+		if (uo.fu_type == EMPTY)
+			continue;
+
+		/* Write new entry to output file. */
+		for (l = sizeof uo; l > 0 &&
+		    ((const char *)&uo)[l - 1] == '\0'; l--);
+		lo = htobe16(l);
+		fwrite(&lo, sizeof lo, 1, out);
+		fwrite(&uo, l, 1, out);
+	}
+
+	fclose(in);
+	fclose(out);
+	return (0);
+}