diff --git a/Doc/whatsnew/3.12.rst b/Doc/whatsnew/3.12.rst
index 8bc7e8a630e2a6..fcfd034b03903b 100644
--- a/Doc/whatsnew/3.12.rst
+++ b/Doc/whatsnew/3.12.rst
@@ -1498,6 +1498,9 @@ Changes in the Python API
   * Some incomplete or invalid Python code now raises :exc:`tokenize.TokenError` instead of
     returning arbitrary ``ERRORTOKEN`` tokens when tokenizing it.
 
+  * Mixing tabs and spaces as indentation in the same file is not supported anymore and will
+    raise a :exc:`TabError`.
+
 Build Changes
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