diff --git a/sbin/newfs/newfs.8 b/sbin/newfs/newfs.8
index 6416e0f0ec8..3aa3890479b 100644
--- a/sbin/newfs/newfs.8
+++ b/sbin/newfs/newfs.8
@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd January 7, 2026
+.Dd March 20, 2026
 .Dt NEWFS 8
 .Os
 .Sh NAME
@@ -84,6 +84,8 @@ Enable journaling on the new file system via gjournal.
 See
 .Xr gjournal 8
 for details.
+This is incompatible with soft updates
+.Pq Fl U .
 .It Fl L Ar volname
 Add a volume label to the new file system.
 Legal characters are alphanumerics, dashes, and underscores.
@@ -98,12 +100,14 @@ The default format is UFS2.
 For backward compatibility.
 .It Fl U
 Enable soft updates on the new file system.
+This is incompatible with GEOM journaling
+.Pq Fl J .
 If neither
 .Fl U
 nor
 .Fl u
 is specified, soft updates are enabled by default for UFS2 format file
-systems and disabled otherwise.
+systems unless GEOM journaling was requested and disabled otherwise.
 .It Fl u
 Do not enable soft updates on the new file system.
 If neither
@@ -176,8 +180,10 @@ One inode is required for each distinct file, so this value effectively
 specifies the average file size on the file system.
 .It Fl j
 Enable soft updates journaling on the new file system.
-This implies
-.Fl U .
+This implies soft updates
+.Pq Fl U
+and is incompatible with GEOM journaling
+.Pq Fl J .
 This flag is implemented by running the
 .Xr tunefs 8
 utility found in the user's
diff --git a/sbin/newfs/newfs.c b/sbin/newfs/newfs.c
index 78f0bfcf458..a54aae6ef6f 100644
--- a/sbin/newfs/newfs.c
+++ b/sbin/newfs/newfs.c
@@ -390,7 +390,9 @@ main(int argc, char *argv[])
 	}
 	/* Use soft updates by default for UFS2 and above */
 	if (Uflag < 0)
-		Uflag = Oflag > 1;
+		Uflag = Oflag > 1 && !Jflag;
+	if (Uflag && Jflag)
+		errx(1, "Cannot enable both soft updates and GEOM journaling");
 	realsectorsize = sectorsize;
 	if (sectorsize != DEV_BSIZE) {		/* XXX */
 		int secperblk = sectorsize / DEV_BSIZE;