diff --git a/main.go b/main.go
index dfb700d..7e38805 100644
--- a/main.go
+++ b/main.go
@@ -20,12 +20,17 @@ import (
 func main() {
 	useClient := flag.Bool("c", false, "Run client")
 
-	keyPath := flag.String("key", "", "Path to the private (client mode) or public (server mode) to use")
+	keyPath := flag.String("key", "", "Path to the private key (client mode) or public key (server mode) to use - Required")
 
 	simulateCaddy := flag.Bool("caddy", false, "Simulate caddy reverse proxy")
 
 	flag.Parse()
 
+	if *keyPath == "" {
+		flag.PrintDefaults()
+		return
+	}
+
 	if *useClient {
 		runClient(keyPath, *simulateCaddy)
 	} else {