diff --git a/CHANGES.rst b/CHANGES.rst
index df0cb00..0b689dc 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,8 +1,19 @@
 Changes
 =======
 
+v0.4.1
+------
+Released October 7, 2020
+
+* Fix implementation error in Grism model dispersion calculations
+
 v0.4.0
 ------
+.. warning::
+
+  The Grism model updates are broken in this release. It has been yanked from 
+  PyPi. The issue is fixed in v0.4.1.
+
 Released October 6, 2020
 
 * Update Grism model to use correct definition of dispersion, accomodate
diff --git a/lentil/__init__.py b/lentil/__init__.py
index a724690..f58d5bf 100644
--- a/lentil/__init__.py
+++ b/lentil/__init__.py
@@ -8,4 +8,4 @@
 from lentil import wfe
 from lentil import zernike
 
-__version__ = '0.4.0'
+__version__ = '0.4.1'