diff --git a/core/src/main/scala/kafka/tools/KafkaMigrationTool.java b/core/src/main/scala/kafka/tools/KafkaMigrationTool.java
index 95fbe46..85339d3 100644
--- a/core/src/main/scala/kafka/tools/KafkaMigrationTool.java
+++ b/core/src/main/scala/kafka/tools/KafkaMigrationTool.java
@@ -251,9 +251,11 @@ public class KafkaMigrationTool {
         thread.start();
         migrationThreads.add(thread);
       }
+
+      String clientIdKey = "client.id";
       // start producer threads
       for (int i = 0; i < numProducers; i++) {
-        kafkaProducerProperties_08.put("client.id", String.valueOf(i) + "-" + i);
+        kafkaProducerProperties_08.put(clientIdKey, kafkaProducerProperties_08.getProperty(clientIdKey) + "-" + i);
         ProducerConfig producerConfig_08 = new ProducerConfig(kafkaProducerProperties_08);
         Producer producer = new Producer(producerConfig_08);
         ProducerThread producerThread = new ProducerThread(producerDataChannel, producer, i);