diff --git a/sbin/fsck_msdosfs/fsck_msdosfs.8 b/sbin/fsck_msdosfs/fsck_msdosfs.8
--- a/sbin/fsck_msdosfs/fsck_msdosfs.8
+++ b/sbin/fsck_msdosfs/fsck_msdosfs.8
@@ -23,7 +23,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd January 6, 2020
+.Dd December 18, 2024
 .Dt FSCK_MSDOSFS 8
 .Os
 .Sh NAME
@@ -32,10 +32,10 @@
 .Sh SYNOPSIS
 .Nm
 .Fl p
-.Op Fl Cf
+.Op Fl BCf
 .Ar filesystem ...
 .Nm
-.Op Fl CMny
+.Op Fl BCMny
 .Ar filesystem ...
 .Sh DESCRIPTION
 The
@@ -71,6 +71,10 @@
 .Pp
 The options are as follows:
 .Bl -tag -width indent
+.It Fl B
+Compatibility with the corresponding
+.Xr fsck 8
+option (perform the check in the background), defined to no-op.
 .It Fl C
 Compatibility with the corresponding
 .Xr fsck 8
diff --git a/sbin/fsck_msdosfs/main.c b/sbin/fsck_msdosfs/main.c
--- a/sbin/fsck_msdosfs/main.c
+++ b/sbin/fsck_msdosfs/main.c
@@ -68,9 +68,10 @@
 
 	skipclean = 1;
 	allow_mmap = 1;
-	while ((ch = getopt(argc, argv, "CfFnpyM")) != -1) {
+	while ((ch = getopt(argc, argv, "BCfFnpyM")) != -1) {
 		switch (ch) {
-		case 'C': /* for fsck_ffs compatibility */
+		case 'B': /* for fsck_ffs compatibility */
+		case 'C':
 			break;
 		case 'f':
 			skipclean = 0;