diff --git a/man/mkfs.btrfs.8.in b/man/mkfs.btrfs.8.in
index 548e754f..b54e9354 100644
--- a/man/mkfs.btrfs.8.in
+++ b/man/mkfs.btrfs.8.in
@@ -7,11 +7,11 @@ mkfs.btrfs \- create a btrfs filesystem
 [ \fB\-b\fP\fI byte-count\fP ]
 [ \fB\-d\fP\fI data-profile\fP ]
 [ \fB\-f\fP ]
+[ \fB\-n\fP\fI nodesize\fP ]
 [ \fB\-l\fP\fI leafsize\fP ]
 [ \fB\-L\fP\fI label\fP ]
 [ \fB\-m\fP\fI metadata profile\fP ]
 [ \fB\-M\fP\fI mixed data+metadata\fP ]
-[ \fB\-n\fP\fI nodesize\fP ]
 [ \fB\-s\fP\fI sectorsize\fP ]
 [ \fB\-r\fP\fI rootdir\fP ]
 [ \fB\-K\fP ]
@@ -45,9 +45,12 @@ Force overwrite when an existing filesystem is detected on the device.
 By default, mkfs.btrfs will not write to the device if it suspects that 
 there is a filesystem or partition table on the device already.
 .TP
+\fB\-n\fR, \fB\-\-nodesize \fIsize\fR
 \fB\-l\fR, \fB\-\-leafsize \fIsize\fR
-Specify the leaf size, the least data item in which btrfs stores data. The
-default value is the page size.
+Specify the nodesize, the tree block size in which btrfs stores data. The
+default value is the page size. Must be a multiple of the sectorsize, but
+not larger than 65536. Leafsize always equals nodesize and the options are
+aliases.
 .TP
 \fB\-L\fR, \fB\-\-label \fIname\fR
 Specify a label for the filesystem.
@@ -66,11 +69,12 @@ utilization.  This feature incurs a performance penalty in
 larger filesystems.  It is recommended for use with filesystems
 of 1 GiB or smaller.
 .TP
-\fB\-n\fR, \fB\-\-nodesize \fIsize\fR
-Specify the nodesize. By default the value is set to the pagesize.
-.TP
 \fB\-s\fR, \fB\-\-sectorsize \fIsize\fR
-Specify the sectorsize, the minimum block allocation.
+Specify the sectorsize, the minimum data block allocation unit. The default
+value is the page size. If the sectorsize differs from the page size, the
+created filesystem may not be mountable by current kernel. Therefore it is not
+recommended to use this option unless you are going to mount it on a system
+with the appropriate page size.
 .TP
 \fB\-r\fR, \fB\-\-rootdir \fIrootdir\fR
 Specify a directory to copy into the newly created fs.
diff --git a/mkfs.c b/mkfs.c
index b4607ae0..5238b897 100644
--- a/mkfs.c
+++ b/mkfs.c
@@ -319,7 +319,7 @@ static void print_usage(void)
 	fprintf(stderr, "\t -m --metadata metadata profile, values like data profile\n");
 	fprintf(stderr, "\t -M --mixed mix metadata and data together\n");
 	fprintf(stderr, "\t -n --nodesize size of btree nodes\n");
-	fprintf(stderr, "\t -s --sectorsize min block allocation\n");
+	fprintf(stderr, "\t -s --sectorsize min block allocation (may not mountable by current kernel)\n");
 	fprintf(stderr, "\t -r --rootdir the source directory\n");
 	fprintf(stderr, "\t -K --nodiscard do not perform whole device TRIM\n");
 	fprintf(stderr, "\t -O --features comma separated list of filesystem features\n");