diff --git a/entrypoint.core.sh.tmpl b/entrypoint.core.sh.tmpl
index e34dd6a..e4fe3d1 100644
--- a/entrypoint.core.sh.tmpl
+++ b/entrypoint.core.sh.tmpl
@@ -34,6 +34,11 @@ file_env "MAILMAN_REST_PASSWORD"
 
 export DATABASE_URL="postgres://${DATABASE_USER}:${DATABASE_PASSWORD}@${DATABASE_HOST}/${DATABASE_NAME}"
 
+# Diabolical hack to remove duplicate hostnames due to Docker shared networks
+# See https://git.autonomic.zone/coop-cloud/mailu/src/branch/main/compose.yml for more
+sed "/192.168/d" /etc/hosts > /etc/hosts-single-hostname
+cat /etc/hosts-single-hostname > /etc/hosts
+
 # --- upstream entrypoint below ---
 
 function wait_for_postgres () {