diff --git a/symfony/mailer/4.3/manifest.json b/symfony/mailer/4.3/manifest.json
index 778e5f68..c1f64c49 100644
--- a/symfony/mailer/4.3/manifest.json
+++ b/symfony/mailer/4.3/manifest.json
@@ -10,7 +10,7 @@
             "services": [
                 "mailer:",
                 "  image: schickling/mailcatcher",
-                "  ports: [1025, 1080]"
+                "  ports: [\"1025\", \"1080\"]"
             ]
         }
     },