diff --git a/lib/libc/sys/Makefile.inc b/lib/libc/sys/Makefile.inc
index 885f64f8653e..9e1eb58fb9ca 100644
--- a/lib/libc/sys/Makefile.inc
+++ b/lib/libc/sys/Makefile.inc
@@ -1,5 +1,5 @@
 #	@(#)Makefile.inc	8.3 (Berkeley) 10/24/94
-#	$Id: Makefile.inc,v 1.45 1998/01/31 05:53:57 imp Exp $
+#	$Id: Makefile.inc,v 1.47 1998/03/09 07:22:12 jb Exp $
 
 # sys sources
 .PATH: ${.CURDIR}/../libc/${MACHINE_ARCH}/sys ${.CURDIR}/../libc/sys
@@ -22,7 +22,7 @@
 # If using the NetBSD syscall interface add sources that convert
 # the NetBSD interface to the one FreeBSD expects:
 .if defined(NETBSD_SYSCALLS)
-SRCS+=	netbsd_getdirentries.c netbsd_stat.c
+SRCS+=	netbsd_getdirentries.c netbsd_msync.c netbsd_stat.c
 .endif
 
 # Sources common to both syscall interfaces:
diff --git a/lib/libc/sys/netbsd_msync.c b/lib/libc/sys/netbsd_msync.c
new file mode 100644
index 000000000000..4461f229b140
--- /dev/null
+++ b/lib/libc/sys/netbsd_msync.c
@@ -0,0 +1,57 @@
+/* $Id$
+ *
+ * Copyright (c) 1998 John Birrell <jb@cimlogic.com.au>.
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by John Birrell.
+ * 4. Neither the name of the author nor the names of any co-contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL 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 REGENTS 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/types.h>
+#include <sys/mman.h>
+
+/* NetBSD uses a different syscall and the flags use different numbers! */
+int	__msync13 __P((void *, size_t, int));
+
+int
+msync(void *addr, size_t size, int nflags)
+{
+	int flags = 0;
+
+	/* Convert FreeBSD flags to NetBSD flags (sigh): */
+	if (nflags & MS_ASYNC)
+		/* MS_ASYNC: */
+		flags |= 0x01;
+	else
+		/* MS_SYNC: */
+		flags |= 0x04;
+	if (nflags & MS_INVALIDATE)
+		flags |= 0x02;
+
+	/* Perform the syscall: */
+	return(__msync13(addr, size, flags));
+}