diff --git a/README.md b/README.md
index c1f8c0ec..1ed9e04e 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,8 @@ For details on the latest updates, see the [Changelog](https://github.com/Unidat
  See discussion for issue [#198](https://github.com/Unidata/cftime/issues/198).
  The calendar specific sub-classes are now deprecated, but remain for now
  as stubs that just instantiate the base class and override `__repr__`.
+ The default calendar in `cftime.date2num` has been changed from `'standard'` to `None`
+ (the calendar associated with first input datetime object is used to define the calendar).
 
 07/20/2020: Version 1.2.1 released.  Fixes a couple of regressions introduced in 1.2.0. See Changelog for details.