diff --git a/doc/manuals/osmosgsn-usermanual.adoc b/doc/manuals/osmosgsn-usermanual.adoc
index 12a7b87..79c94f6 100644
--- a/doc/manuals/osmosgsn-usermanual.adoc
+++ b/doc/manuals/osmosgsn-usermanual.adoc
@@ -1,3 +1,5 @@
+:gfdl-enabled:
+
 OsmoSGSN User Manual
 ====================
 Harald Welte <hwelte@sysmocom.de>
