diff --git a/use/identifying_to_services.rst b/use/identifying_to_services.rst
index d9ee40b..48077d1 100644
--- a/use/identifying_to_services.rst
+++ b/use/identifying_to_services.rst
@@ -65,6 +65,11 @@ the real network name like ``freenode``.
 CertFP
 ------
 
+Please note that there is a bug
+(https://github.com/ProgVal/Limnoria/issues/1052) that requires you to
+configure ``networks.<network>.sasl.username`` before SASL EXTERNAL is
+attempted.
+
 You can test if CertFP is supported by services simply by doing
 ``/msg NickServ cert``. If you get an error about "Insufficient parameters
 for CERT", CertFP is supported, and if you get an error about unknown