diff --git a/CHANGES b/CHANGES
index 7add2c4b0..b7f125b47 100644
--- a/CHANGES
+++ b/CHANGES
@@ -37,6 +37,8 @@ Bugs fixed
 * #3965: New quickstart generates wrong SPHINXBUILD in Makefile
 * #3739: ``:module:`` option is ignored at content of pyobjects
 * #4149: Documentation: Help choosing :confval:`latex_engine`
+* #4090: [doc] :confval:`latex_additional_files` with extra LaTeX macros should
+  not use ``.tex`` extension
 
 Testing
 --------
diff --git a/doc/latex.rst b/doc/latex.rst
index eaf147c1c..f349b8fc0 100644
--- a/doc/latex.rst
+++ b/doc/latex.rst
@@ -65,14 +65,14 @@ If the size of the ``'preamble'`` contents becomes inconvenient, one may move
 all needed macros into some file :file:`mystyle.tex` of the project source
 repertory, and get LaTeX to import it at run time::
 
-   'preamble': r'\input{mystyle.tex}',
+   'preamble': r'\input{mystyle.tex.txt}',
    # or, if the \ProvidesPackage LaTeX macro is used in a file mystyle.sty
    'preamble': r'\usepackage{mystyle}',
 
 It is needed to set appropriately :confval:`latex_additional_files`, for
 example::
 
-   latex_additional_files = ["mystyle.tex"]
+   latex_additional_files = ["mystyle.sty"]
 
 .. _latexsphinxsetup: