diff --git a/sys/fs/msdosfs/denode.h b/sys/fs/msdosfs/denode.h
index ea92bd18e537..e54f79b103d8 100644
--- a/sys/fs/msdosfs/denode.h
+++ b/sys/fs/msdosfs/denode.h
@@ -1,4 +1,4 @@
-/*	$NetBSD: denode.h,v 1.5 2005/07/23 12:18:41 yamt Exp $	*/
+/*	$NetBSD: denode.h,v 1.6 2005/08/29 23:22:05 xtraeme Exp $	*/
 
 /*-
  * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
@@ -177,6 +177,9 @@ struct denode {
  */
 #define	WIN_MAXLEN	255
 
+/* Maximum size of a file on a FAT filesystem */
+#define MSDOSFS_FILESIZE_MAX	0xFFFFFFFFLL
+
 /*
  * Transfer directory entries between internal and external form.
  * dep is a struct denode * (internal form),
diff --git a/sys/fs/msdosfs/msdosfs_vnops.c b/sys/fs/msdosfs/msdosfs_vnops.c
index 4234f16dbce4..92997920f3c4 100644
--- a/sys/fs/msdosfs/msdosfs_vnops.c
+++ b/sys/fs/msdosfs/msdosfs_vnops.c
@@ -1,4 +1,4 @@
-/*	$NetBSD: msdosfs_vnops.c,v 1.16 2005/08/19 12:24:54 christos Exp $	*/
+/*	$NetBSD: msdosfs_vnops.c,v 1.17 2005/08/29 23:22:05 xtraeme Exp $	*/
 
 /*-
  * Copyright (C) 1994, 1995, 1997 Wolfgang Solfrank.
@@ -48,7 +48,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: msdosfs_vnops.c,v 1.16 2005/08/19 12:24:54 christos Exp $");
+__KERNEL_RCSID(0, "$NetBSD: msdosfs_vnops.c,v 1.17 2005/08/29 23:22:05 xtraeme Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -597,6 +597,10 @@ msdosfs_write(v)
 	if (uio->uio_resid == 0)
 		return (0);
 
+	/* Don't bother to try to write files larger than the fs limit */
+	if (uio->uio_offset + uio->uio_resid > MSDOSFS_FILESIZE_MAX)
+		return (EFBIG);
+
 	/*
 	 * If they've exceeded their filesize limit, tell them about it.
 	 */