diff --git a/config.dev.toml b/config.dev.toml
index 6939dc36..6554969f 100644
--- a/config.dev.toml
+++ b/config.dev.toml
@@ -62,6 +62,7 @@ StorageType = "memory"
 
 # Port sets the port the proxy listens on
 # Env override: PORT
+# Note that PORT needs to be prefixed by :
 Port = ":3000"
 
 # The endpoint for a package registry in case of a proxy cache miss