diff --git a/Documentation/gpu/conf.py b/Documentation/gpu/conf.py
index d60bcd0..6314d17 100644
--- a/Documentation/gpu/conf.py
+++ b/Documentation/gpu/conf.py
@@ -1,3 +1,5 @@
 # -*- coding: utf-8; mode: python -*-
 
 project = "Linux GPU Driver Developer's Guide"
+
+tags.add("subproject")