diff --git a/usr.sbin/makefs/ffs/mkfs.c b/usr.sbin/makefs/ffs/mkfs.c
--- a/usr.sbin/makefs/ffs/mkfs.c
+++ b/usr.sbin/makefs/ffs/mkfs.c
@@ -451,10 +451,8 @@
 	sblock.fs_cstotal.cs_nifree = 0;
 	sblock.fs_cstotal.cs_nffree = 0;
 	sblock.fs_fmod = 0;
-	sblock.fs_ronly = 0;
 	sblock.fs_state = 0;
 	sblock.fs_clean = FS_ISCLEAN;
-	sblock.fs_ronly = 0;
 	sblock.fs_id[0] = tstamp;
 	sblock.fs_id[1] = random();
 	sblock.fs_fsmnt[0] = '\0';
@@ -482,6 +480,10 @@
 		sblock.fs_old_cstotal.cs_nifree = sblock.fs_cstotal.cs_nifree;
 		sblock.fs_old_cstotal.cs_nffree = sblock.fs_cstotal.cs_nffree;
 	}
+	/* Read-Only Flag */
+	sblock.fs_ronly = 0;
+	if (fsopts->ronly)
+		sblock.fs_ronly = 1;
 	/*
 	 * Dump out summary information about file system.
 	 */
diff --git a/usr.sbin/makefs/makefs.h b/usr.sbin/makefs/makefs.h
--- a/usr.sbin/makefs/makefs.h
+++ b/usr.sbin/makefs/makefs.h
@@ -162,6 +162,7 @@
 	int	needswap;	/* non-zero if byte swapping needed */
 	int	sectorsize;	/* sector size */
 	int	sparse;		/* sparse image, don't fill it with zeros */
+	int     ronly;          /* read-only (ro) flag */
 
 	void	*fs_specific;	/* File system specific additions. */
 	option_t *fs_options;	/* File system specific options */
diff --git a/usr.sbin/makefs/makefs.8 b/usr.sbin/makefs/makefs.8
--- a/usr.sbin/makefs/makefs.8
+++ b/usr.sbin/makefs/makefs.8
@@ -219,6 +219,8 @@
 This option only applies to the
 .Sy ffs
 file system type.
+.It Fl r Ar read-only mode
+Sets the ffs read-only mode flag.
 .It Fl S Ar sector-size
 Set the file system sector size to
 .Ar sector-size .
diff --git a/usr.sbin/makefs/makefs.c b/usr.sbin/makefs/makefs.c
--- a/usr.sbin/makefs/makefs.c
+++ b/usr.sbin/makefs/makefs.c
@@ -130,7 +130,7 @@
 		err(1, "Unable to get system time");
 
 
-	while ((ch = getopt(argc, argv, "B:b:Dd:f:F:M:m:N:O:o:pR:s:S:t:T:xZ")) != -1) {
+	while ((ch = getopt(argc, argv, "B:b:Dd:f:F:M:m:N:O:o:pR:rs:S:t:T:xZ")) != -1) {
 		switch (ch) {
 
 		case 'B':
@@ -237,6 +237,10 @@
 			    strsuftoll("roundup-size", optarg, 0, LLONG_MAX);
 			break;
 
+		case 'r':
+			fsoptions.ronly = 1;
+			break;
+
 		case 's':
 			fsoptions.minsize = fsoptions.maxsize =
 			    strsuftoll("size", optarg, 1LL, LLONG_MAX);
@@ -488,7 +492,7 @@
 
 	prog = getprogname();
 	fprintf(stderr,
-"Usage: %s [-xZ] [-B endian] [-b free-blocks] [-d debug-mask]\n"
+"Usage: %s [-rxZ] [-B endian] [-b free-blocks] [-d debug-mask]\n"
 "\t[-F mtree-specfile] [-f free-files] [-M minimum-size] [-m maximum-size]\n"
 "\t[-N userdb-dir] [-O offset] [-o fs-options] [-R roundup-size]\n"
 "\t[-S sector-size] [-s image-size] [-T <timestamp/file>] [-t fs-type]\n"