diff --git a/mercurial/revset.py b/mercurial/revset.py
--- a/mercurial/revset.py
+++ b/mercurial/revset.py
@@ -2411,13 +2411,13 @@ class baseset(abstractsmartset):
         """Returns True if the collection is ascending order, False if not.
 
         This is part of the mandatory API for smartset."""
-        return False
+        return self._ascending is not None and self._ascending
 
     def isdescending(self):
         """Returns True if the collection is descending order, False if not.
 
         This is part of the mandatory API for smartset."""
-        return False
+        return self._ascending is not None and not self._ascending
 
     def first(self):
         if self: