diff --git a/config/prod.secret.exs b/config/prod.secret.exs
index f0adf089..038f61d4 100644
--- a/config/prod.secret.exs
+++ b/config/prod.secret.exs
@@ -61,7 +61,7 @@ secret_key_base =
     """
 
 config :philomena, PhilomenaWeb.Endpoint,
-  http: [ip: {127, 0, 0, 1}, port: String.to_integer(System.get_env("PORT") || "4000")],
+  http: [ip: {127, 0, 0, 1}, port: {:system, "PORT"}],
   url: [host: System.get_env("APP_HOSTNAME"), scheme: "https", port: 443],
   secret_key_base: secret_key_base,
   server: true