diff --git a/docs/_toc.yml b/docs/_toc.yml
deleted file mode 100644
index bb8f5a9..0000000
--- a/docs/_toc.yml
+++ /dev/null
@@ -1,3 +0,0 @@
-root: index
-entries:
-  - glob: lecture*
diff --git a/docs/conf.py b/docs/conf.py
index 442852c..92adcad 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -32,11 +32,8 @@ def get_execution_mode() -> str:
     "sphinx_copybutton",
     "sphinx_design",
     "sphinx_exercise",
-    "sphinx_external_toc",
     "sphinx_togglebutton",
 ]
-external_toc_exclude_missing = True
-external_toc_path = "_toc.yml"
 html_favicon = "_static/favicon.ico"
 html_js_files = [
     "https://cdnjs.cloudflare.com/ajax/libs/require.js/2.3.4/require.min.js"
diff --git a/docs/index.md b/docs/index.md
index 0a9f8c5..11a3094 100644
--- a/docs/index.md
+++ b/docs/index.md
@@ -3,5 +3,8 @@
 
 ## Table of contents
 
-:::{tableofcontents}
-:::
+```{toctree}
+:glob:
+:maxdepth: 2
+lecture*
+```
diff --git a/pyproject.toml b/pyproject.toml
index 54e962b..41527d8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -48,8 +48,8 @@ doc = [
     "sphinx-copybutton",
     "sphinx-design",
     "sphinx-exercise",
-    "sphinx-external-toc",
     "sphinx-togglebutton",
+    "sphinx<6", # https://github.com/ComPWA/strong2020-salamanca/issues/29
 ]
 format = [
     "black",