diff --git a/doc/utils/requirements.txt b/doc/utils/requirements.txt
index fbb161baa5..90f7fdf3f6 100644
--- a/doc/utils/requirements.txt
+++ b/doc/utils/requirements.txt
@@ -2,6 +2,7 @@ Sphinx >= 5.3.0, <8.3.0
 sphinxcontrib-spelling
 sphinxcontrib-jquery
 sphinx-design
+sphinx-toolbox
 git+https://github.com/akohlmey/sphinx-fortran@parallel-read
 sphinx-tabs>=3.4.1
 breathe
diff --git a/doc/utils/sphinx-config/conf.py.in b/doc/utils/sphinx-config/conf.py.in
index 3a7f19e5a8..6039b3610e 100644
--- a/doc/utils/sphinx-config/conf.py.in
+++ b/doc/utils/sphinx-config/conf.py.in
@@ -50,6 +50,7 @@ extensions = [
     'sphinx.ext.mathjax',
     'sphinx.ext.imgmath',
     'sphinx.ext.autodoc',
+    'sphinx_toolbox.collapse',
     'lammps_theme',
     'sphinxcontrib.jquery',
     'sphinxfortran.fortran_domain',