diff --git a/settings.py.sample b/settings.py.sample
index 0728901c7bcf5c6c76e8895e4f3388822a238c8c..7fe210b0c311e81388d29d2e1e87efc9577035b2 100644
--- a/settings.py.sample
+++ b/settings.py.sample
@@ -109,6 +109,9 @@ LOGOUT_ON_CONFIRMATION = True
 # The two hosts are here so the main site can be over plain HTTP
 # while the voting URLs are served over SSL.
 URL_HOST = "http://localhost:8000"
+
+# IMPORTANT: you should not change this setting once you've created
+# elections, as your elections' cast_url will then be incorrect.
 SECURE_URL_HOST = "https://localhost:8443"
 
 # this additional host is used to iframe-isolate the social buttons,