diff --git a/sys/kern/syscalls.master b/sys/kern/syscalls.master
index 433f6820f245..376ab40b4663 100644
--- a/sys/kern/syscalls.master
+++ b/sys/kern/syscalls.master
@@ -1,4 +1,4 @@
-	$NetBSD: syscalls.master,v 1.75 1998/05/30 22:21:03 kleink Exp $
+	$NetBSD: syscalls.master,v 1.76 1998/06/05 20:31:36 kleink Exp $
 
 ;	@(#)syscalls.master	8.2 (Berkeley) 1/13/94
 
@@ -476,7 +476,7 @@
 ;
 240	STD		{ int sys_nanosleep(const struct timespec *rqtp, \
 			    struct timespec *rmtp); }
-241	UNIMPL		fktrace
+241	STD		{ int sys_fdatasync(int fd); }
 242	UNIMPL
 243	UNIMPL
 244	UNIMPL
diff --git a/sys/kern/vfs_syscalls.c b/sys/kern/vfs_syscalls.c
index ff3a7486b5c1..3d5cbb4e6b1f 100644
--- a/sys/kern/vfs_syscalls.c
+++ b/sys/kern/vfs_syscalls.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: vfs_syscalls.c,v 1.116 1998/06/05 20:04:15 kleink Exp $	*/
+/*	$NetBSD: vfs_syscalls.c,v 1.117 1998/06/05 20:31:36 kleink Exp $	*/
 
 /*
  * Copyright (c) 1989, 1993
@@ -2014,6 +2014,32 @@ sys_fsync(p, v, retval)
 	return (error);
 }
 
+/*
+ * Sync the data of an open file.
+ */
+/* ARGSUSED */
+int
+sys_fdatasync(p, v, retval)
+	struct proc *p;
+	void *v;
+	register_t *retval;
+{
+	struct sys_fdatasync_args /* {
+		syscallarg(int) fd;
+	} */ *uap = v;
+	struct vnode *vp;
+	struct file *fp;
+	int error;
+
+	if ((error = getvnode(p->p_fd, SCARG(uap, fd), &fp)) != 0)
+		return (error);
+	vp = (struct vnode *)fp->f_data;
+	vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
+	error = VOP_FSYNC(vp, fp->f_cred, FSYNC_WAIT|FSYNC_DATAONLY, p);
+	VOP_UNLOCK(vp, 0);
+	return (error);
+}
+
 /*
  * Rename files, (standard) BSD semantics frontend.
  */