diff --git a/cli.go b/cli.go
index 366a7a6..df4af02 100644
--- a/cli.go
+++ b/cli.go
@@ -19,7 +19,7 @@ func (cli *CLI) printUsage() {
 	fmt.Println("  printchain - Print all the blocks of the blockchain")
 	fmt.Println("  reindexutxo - Rebuilds the UTXO set")
 	fmt.Println("  send -from FROM -to TO -amount AMOUNT - Send AMOUNT of coins from FROM address to TO")
-	fmt.Println("  startnode -node-id NODE_ID - Start a node with specified ID")
+	fmt.Println("  startnode - Start a node with ID specified in NODE_ID env. var")
 }
 
 func (cli *CLI) validateArgs() {
@@ -47,7 +47,6 @@ func (cli *CLI) Run() {
 	sendFrom := sendCmd.String("from", "", "Source wallet address")
 	sendTo := sendCmd.String("to", "", "Destination wallet address")
 	sendAmount := sendCmd.Int("amount", 0, "Amount to send")
-	startNodeID := startNodeCmd.Int("node-id", 0, "Node ID")
 
 	switch os.Args[1] {
 	case "getbalance":
@@ -137,10 +136,11 @@ func (cli *CLI) Run() {
 	}
 
 	if startNodeCmd.Parsed() {
-		if *startNodeID == 0 {
+		nodeID := os.Getenv("NODE_ID")
+		if nodeID == "" {
 			startNodeCmd.Usage()
 			os.Exit(1)
 		}
-		cli.startNode(*startNodeID)
+		cli.startNode(nodeID)
 	}
 }
diff --git a/cli_startnode.go b/cli_startnode.go
index 5b64f3c..289ccd4 100644
--- a/cli_startnode.go
+++ b/cli_startnode.go
@@ -2,7 +2,7 @@ package main
 
 import "fmt"
 
-func (cli *CLI) startNode(nodeID int) {
-	fmt.Printf("Starting node %d\n", nodeID)
+func (cli *CLI) startNode(nodeID string) {
+	fmt.Printf("Starting node %s\n", nodeID)
 	StartServer(nodeID)
 }
diff --git a/server.go b/server.go
index a071ba0..ba0906d 100644
--- a/server.go
+++ b/server.go
@@ -11,7 +11,7 @@ import (
 )
 
 const protocol = "tcp"
-const dnsNodeID = 3000
+const dnsNodeID = "3000"
 const nodeVersion = 1
 const commandLength = 12
 
@@ -149,8 +149,8 @@ func handleConnection(conn net.Conn) {
 }
 
 // StartServer starts a node
-func StartServer(nodeID int) {
-	nodeAddress = fmt.Sprintf("localhost:%d", nodeID)
+func StartServer(nodeID string) {
+	nodeAddress = fmt.Sprintf("localhost:%s", nodeID)
 	ln, err := net.Listen(protocol, nodeAddress)
 	if err != nil {
 		log.Panic(err)
@@ -158,7 +158,7 @@ func StartServer(nodeID int) {
 	defer ln.Close()
 
 	if nodeID != dnsNodeID {
-		sendVersion(fmt.Sprintf("localhost:%d", dnsNodeID))
+		sendVersion(fmt.Sprintf("localhost:%s", dnsNodeID))
 	}
 
 	for {