diff --git a/lib/ssconf.py b/lib/ssconf.py
index bdfcfdd75abc1793ee833c9115e8aa8dc25546db..120d85d6ce6a9559990ae3f712dedeeda493efe6 100644
--- a/lib/ssconf.py
+++ b/lib/ssconf.py
@@ -178,7 +178,8 @@ class SimpleStore:
   def SetKey(self, key, value):
     """Set the value of a key.
 
-    This should be used only when adding a node to a cluster.
+    This should be used only when adding a node to a cluster, or in other
+    infrequent operations such as cluster-rename or master-failover.
 
     """
     file_name = self.KeyToFilename(key)