diff --git a/WHATS_NEW b/WHATS_NEW
index 44682a6eb..e39a36e4e 100644
--- a/WHATS_NEW
+++ b/WHATS_NEW
@@ -1,5 +1,6 @@
 Version 2.02.98 -
 =================================
+  Disallow convertion of thins to mirrors.
   Fix lvm2api data_percent reporting for thin volumes.
   Do not allow RAID LVs in a clustered volume group.
   Update lvconvert to support stacking of devs for thin meta/data devs.
diff --git a/tools/lvconvert.c b/tools/lvconvert.c
index 41bc585d4..132a69db0 100644
--- a/tools/lvconvert.c
+++ b/tools/lvconvert.c
@@ -1494,6 +1494,13 @@ static int _lvconvert_mirrors(struct cmd_context *cmd,
 		return 0;
 	}
 
+	/* TODO: decide what should be done here */
+	if (lv_is_thin_type(lv)) {
+		log_error("Converting segment type for %s/%s to mirror is not yet supported.",
+			 lv->vg->name, lv->name);
+		return 0;
+	}
+
 	/* Adjust mimage and/or log count */
 	if (!_lvconvert_mirrors_parse_params(cmd, lv, lp,
 					     &old_mimage_count, &old_log_count,