diff --git a/docs/index.rst b/docs/index.rst
index d7f1711..d037e27 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -22,7 +22,7 @@ Contents
 --------
 
 .. toctree::
-   :maxdepth: 2
+   :maxdepth: 3
 
    introduction
    api