diff --git a/lib/client/gnt_cluster.py b/lib/client/gnt_cluster.py
index 04fda7341eff00d4fc3bc8ebe565804e2e6f97b2..04c8bbe61b31e32c791a1a258e846e8a928ec988 100644
--- a/lib/client/gnt_cluster.py
+++ b/lib/client/gnt_cluster.py
@@ -1289,7 +1289,7 @@ commands = {
     "", "Does a check on the cluster disk status"),
   "repair-disk-sizes": (
     RepairDiskSizes, ARGS_MANY_INSTANCES, [DRY_RUN_OPT, PRIORITY_OPT],
-    "", "Updates mismatches in recorded disk sizes"),
+    "[instance...]", "Updates mismatches in recorded disk sizes"),
   "master-failover": (
     MasterFailover, ARGS_NONE, [NOVOTING_OPT],
     "", "Makes the current node the master"),