diff --git a/HISTORY.rst b/HISTORY.rst
index 1f5d4e58..6cbff8b3 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -3,6 +3,11 @@
 Release History
 ---------------
 
+0.6.24-dev0
++++++++++++++++++++
+
+- fix: #943 remove mention of a Px Length subtype
+
 0.6.23 (2023-11-02)
 +++++++++++++++++++
 
diff --git a/src/pptx/util.py b/src/pptx/util.py
index bbe8ac20..fdec7929 100644
--- a/src/pptx/util.py
+++ b/src/pptx/util.py
@@ -7,7 +7,7 @@
 
 
 class Length(int):
-    """Base class for length classes Inches, Emu, Cm, Mm, Pt, and Px.
+    """Base class for length classes Inches, Emu, Cm, Mm, and Pt.
 
     Provides properties for converting length values to convenient units.
     """