diff --git a/server.conf.in b/server.conf.in
index e6b143d3..a02df90c 100644
--- a/server.conf.in
+++ b/server.conf.in
@@ -109,6 +109,7 @@ serverRealm = local
 ; data: URL for images.
 ; The currently recommended CSP is:
 ;   default-src 'self';
+;   frame-src 'self' data:;
 ;   style-src 'self' 'unsafe-inline';
 ;   img-src 'self' data: blob:;
 ;   connect-src 'self' wss://server:port/ws blob:;