diff --git a/src/as/com/threerings/util/Map.as b/src/as/com/threerings/util/Map.as
index 3d24f2e90..db36d83cc 100644
--- a/src/as/com/threerings/util/Map.as
+++ b/src/as/com/threerings/util/Map.as
@@ -34,6 +34,8 @@ public interface Map
 
     /**
      * Return all the unique keys in this Map, in Array form.
+     * The Array is not a 'view': it can be modified without disturbing
+     * the Map from whence it came.
      */
     function keys () :Array;
 
@@ -56,6 +58,8 @@ public interface Map
 
     /**
      * Return all the values in this Map, in Array form.
+     * The Array is not a 'view': it can be modified without disturbing
+     * the Map from whence it came.
      */
     function values () :Array;
 }