diff --git a/connection.js b/connection.js
index ef70e0f2c..e2fa52a3d 100644
--- a/connection.js
+++ b/connection.js
@@ -850,7 +850,7 @@ class Connection {
             default:
                 // RFC5321 section 4.1.1.1
                 // Hostname/domain should appear after 250
-                this.respond(250, `${this.local.host} Hello ${this.get_remote('host')}${this.ehlo_hello_message}`);
+                this.respond(250, `${this.local.host} Hello ${this.get_remote('host')}, ${this.ehlo_hello_message}`);
         }
     }
     ehlo_respond (retval, msg) {