diff --git a/compose.mailman.yml b/compose.mailman.yml
index 3b53aaf..3a9940b 100644
--- a/compose.mailman.yml
+++ b/compose.mailman.yml
@@ -9,8 +9,8 @@ services:
         target: /overrides/postfix.cf
 
 volumes:
+  # https://git.autonomic.zone/coop-cloud/mailman3/src/branch/master/compose.yml
   shared-mailman-core:
-    # https://git.autonomic.zone/coop-cloud/mailman3/src/branch/master/compose.yml
     external: true
     name: ${MAILMAN_CORE_VOLUME}