diff --git a/docs/releasenotes/11.0.0.rst b/docs/releasenotes/11.0.0.rst
index bb6179de8..936a441d9 100644
--- a/docs/releasenotes/11.0.0.rst
+++ b/docs/releasenotes/11.0.0.rst
@@ -77,3 +77,10 @@ others prepare for 3.13, and to ensure Pillow could be used immediately at the r
 of 3.13.0 final (2024-10-01, :pep:`719`).
 
 Pillow 11.0.0 now officially supports Python 3.13.
+
+C-level Flags
+^^^^^^^^^^^^^
+
+Some compiling flags like ``WITH_THREADING``, ``WITH_IMAGECHOPS``, and other
+``WITH_*`` were removed. These flags were not available in the build system,
+but they could be edited in the C source.