diff --git a/.example.env b/.example.env
index 9d8daee..2e39596 100644
--- a/.example.env
+++ b/.example.env
@@ -1,5 +1,5 @@
-# Application Port - KOA server listens on this port (default 3000).
-PORT=3000
+# Application Port - KOA server listens on this port (default 4000).
+RELAYER_PORT=4000
 
 # Environment
 NODE_ENV=development
diff --git a/src/config.ts b/src/config.ts
index 30ab940..c0697d0 100644
--- a/src/config.ts
+++ b/src/config.ts
@@ -59,7 +59,7 @@ const getZeroConfig = (): XdcZeroConfig => {
 };
 
 const config: Config = {
-  port: +(process.env.PORT || 3000),
+  port: +(process.env.RELAYER_PORT || 4000),
   devMode: devMode,
   cronJob: {
     liteJobExpression: "0 */2 * * * *", // every 2min