diff --git a/sbin/newfs_msdos/newfs_msdos.c b/sbin/newfs_msdos/newfs_msdos.c
index b645fb7155b8..1c23b241e638 100644
--- a/sbin/newfs_msdos/newfs_msdos.c
+++ b/sbin/newfs_msdos/newfs_msdos.c
@@ -54,7 +54,7 @@ static const char rcsid[] =
 #define NPB	  2		/* nibbles per byte */
 
 #define DOSMAGIC  0xaa55	/* DOS magic number */
-#define MINBPS	  128		/* minimum bytes per sector */
+#define MINBPS	  512		/* minimum bytes per sector */
 #define MAXSPC	  128		/* maximum sectors per cluster */
 #define MAXNFT	  16		/* maximum number of FATs */
 #define DEFBLK	  4096		/* default block size */
@@ -623,17 +623,17 @@ main(int argc, char *argv[])
 		    setstr(bs->oem, opt_O ? opt_O : "BSD  4.4",
 			   sizeof(bs->oem));
 		    memcpy(img + x1, bootcode, sizeof(bootcode));
-		    mk2(img + bpb.bps - 2, DOSMAGIC);
+		    mk2(img + MINBPS - 2, DOSMAGIC);
 		}
 	    } else if (fat == 32 && bpb.infs != MAXU16 &&
 		       (lsn == bpb.infs ||
 			(bpb.bkbs != MAXU16 &&
 			 lsn == bpb.bkbs + bpb.infs))) {
 		mk4(img, 0x41615252);
-		mk4(img + bpb.bps - 28, 0x61417272);
-		mk4(img + bpb.bps - 24, 0xffffffff);
-		mk4(img + bpb.bps - 20, bpb.rdcl);
-		mk2(img + bpb.bps - 2, DOSMAGIC);
+		mk4(img + MINBPS - 28, 0x61417272);
+		mk4(img + MINBPS - 24, 0xffffffff);
+		mk4(img + MINBPS - 20, bpb.rdcl);
+		mk2(img + MINBPS - 2, DOSMAGIC);
 	    } else if (lsn >= bpb.res && lsn < dir &&
 		       !((lsn - bpb.res) %
 			 (bpb.spf ? bpb.spf : bpb.bspf))) {