diff --git a/config/runtime.exs b/config/runtime.exs
index ca345f4..95fdd43 100644
--- a/config/runtime.exs
+++ b/config/runtime.exs
@@ -77,7 +77,7 @@ if config_env() == :prod do
   config :cannery, Cannery.Mailer,
     adapter: Swoosh.Adapters.SMTP,
     relay: System.get_env("SMTP_HOST") || raise("No SMTP_HOST set!"),
-    port: System.get_env("SMTP_PORT", 587),
+    port: System.get_env("SMTP_PORT", "587"),
     username: System.get_env("SMTP_USERNAME") || raise("No SMTP_USERNAME set!"),
     password: System.get_env("SMTP_PASSWORD") || raise("No SMTP_PASSWORD set!"),
     ssl: System.get_env("SMTP_SSL") == "true",