diff --git a/qpid-jms-client/src/main/java/org/apache/qpid/jms/sasl/ExternalMechanism.java b/qpid-jms-client/src/main/java/org/apache/qpid/jms/sasl/ExternalMechanism.java
index 13d8fc0f2..8abc0bb1c 100644
--- a/qpid-jms-client/src/main/java/org/apache/qpid/jms/sasl/ExternalMechanism.java
+++ b/qpid-jms-client/src/main/java/org/apache/qpid/jms/sasl/ExternalMechanism.java
@@ -16,6 +16,7 @@
  */
 package org.apache.qpid.jms.sasl;
 
+import java.nio.charset.StandardCharsets;
 import java.security.Principal;
 
 /**
@@ -25,7 +26,11 @@ public class ExternalMechanism extends AbstractMechanism {
 
     @Override
     public byte[] getInitialResponse() {
-        return EMPTY;
+        String username = getUsername();
+        if(username == null || username.isEmpty()){
+            return EMPTY;
+          }
+        return username.getBytes(StandardCharsets.UTF_8);
     }
 
     @Override