diff --git a/roles/mail/tasks/main.yml b/roles/mail/tasks/main.yml
index e4511d6..4913037 100644
--- a/roles/mail/tasks/main.yml
+++ b/roles/mail/tasks/main.yml
@@ -22,11 +22,11 @@
       - name: mail
       - name: postgresql
     ports:
-      - 25:25
-      - 143:143
-      - 465:465
-      - 587:587
-      - 993:993
+      - "25:25"
+      - "143:143"
+      - "465:465"
+      - "587:587"
+      - "993:993"
     volumes:
       - maddy:/data
       - /etc/letsencrypt/live/{{ domain }}/fullchain.pem:/etc/tls/fullchain.pem:ro