diff --git a/doc/utils/sphinx-config/conf.py.in b/doc/utils/sphinx-config/conf.py.in
index 0da553d755..0a82f63d5c 100644
--- a/doc/utils/sphinx-config/conf.py.in
+++ b/doc/utils/sphinx-config/conf.py.in
@@ -327,6 +327,7 @@ latex_elements = {
 % Make ToC number fields wider to accommodate sections with >= 100 subsections
 %   or >= 10 subsections with >= 10 subsubsections
 \makeatletter
+\@addtoreset{chapter}{part}
 \renewcommand*{\sphinxtableofcontentshook}{%
   \renewcommand*\l@section{\@dottedtocline{1}{1.5em}{3.1em}}
   \renewcommand*\l@subsection{\@dottedtocline{2}{4.6em}{4.5em}}