diff --git a/doc/snac.8 b/doc/snac.8
index 88fb192..e81103f 100644
--- a/doc/snac.8
+++ b/doc/snac.8
@@ -192,6 +192,11 @@ The email address of the instance administrator (optional).
 The user name of the instance administrator (optional).
 .It Ic short_description
 A textual short description about the instance (optional).
+.It Ic fastcgi
+If set to true,
+.Nm
+will use the FastCGI interface to communicate with the upper level
+http server, that must be configured accordingly.
 .El
 .Pp
 You must restart the server to make effective these changes.