diff --git a/man/man4/zfs.4 b/man/man4/zfs.4
index 566caae7b4..d529147464 100644
--- a/man/man4/zfs.4
+++ b/man/man4/zfs.4
@@ -357,7 +357,10 @@ and the allocation can't actually be satisfied
 When a vdev is added, target this number of metaslabs per top-level vdev.
 .
 .It Sy zfs_vdev_default_ms_shift Ns = Ns Sy 29 Po 512 MiB Pc Pq uint
-Default limit for metaslab size.
+Default lower limit for metaslab size.
+.
+.It Sy zfs_vdev_max_ms_shift Ns = Ns Sy 34 Po 16 GiB Pc Pq uint
+Default upper limit for metaslab size.
 .
 .It Sy zfs_vdev_max_auto_ashift Ns = Ns Sy 14 Pq uint
 Maximum ashift used when optimizing for logical \[->] physical sector size on
diff --git a/module/zfs/vdev.c b/module/zfs/vdev.c
index ad932a7ba7..7cf858c050 100644
--- a/module/zfs/vdev.c
+++ b/module/zfs/vdev.c
@@ -96,7 +96,7 @@ static uint_t zfs_vdev_ms_count_limit = 1ULL << 17;
 static uint_t zfs_vdev_default_ms_shift = 29;
 
 /* upper limit for metaslab size (16G) */
-static const uint_t zfs_vdev_max_ms_shift = 34;
+static uint_t zfs_vdev_max_ms_shift = 34;
 
 int vdev_validate_skip = B_FALSE;
 
@@ -6288,7 +6288,10 @@ ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, default_ms_count, UINT, ZMOD_RW,
 	"Target number of metaslabs per top-level vdev");
 
 ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, default_ms_shift, UINT, ZMOD_RW,
-	"Default limit for metaslab size");
+	"Default lower limit for metaslab size");
+
+ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, max_ms_shift, UINT, ZMOD_RW,
+	"Default upper limit for metaslab size");
 
 ZFS_MODULE_PARAM(zfs_vdev, zfs_vdev_, min_ms_count, UINT, ZMOD_RW,
 	"Minimum number of metaslabs per top-level vdev");