diff --git a/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/Worker.java b/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/Worker.java
index f6af006d..3bad9c5a 100644
--- a/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/Worker.java
+++ b/src/main/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/Worker.java
@@ -32,6 +32,7 @@ import java.util.concurrent.ThreadPoolExecutor;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 
+import com.amazonaws.regions.Regions;
 import org.apache.commons.lang.StringUtils;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
@@ -1163,6 +1164,7 @@ public class Worker implements Runnable {
         private ShardPrioritization shardPrioritization;
         @Setter @Accessors(fluent = true)
         private IKinesisProxy kinesisProxy;
+        @Setter @Accessors(fluent = true)
         private WorkerStateChangeListener workerStateChangeListener;
 
         @VisibleForTesting
@@ -1331,6 +1333,9 @@ public class Worker implements Runnable {
             } else if (StringUtils.isNotEmpty(region)) {
                 LOG.debug("The region for the client has been set to " + region);
                 builder.withRegion(region);
+            } else {
+                LOG.debug("Endpoint URL and region are not set, setting region to us-east-1");
+                builder.withRegion(Regions.US_EAST_1);
             }
             return (AmazonWebServiceClient) builder.build();
         }
diff --git a/src/test/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/WorkerTest.java b/src/test/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/WorkerTest.java
index 0205b03a..6b2eae69 100644
--- a/src/test/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/WorkerTest.java
+++ b/src/test/java/com/amazonaws/services/kinesis/clientlibrary/lib/worker/WorkerTest.java
@@ -19,7 +19,6 @@ import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.CoreMatchers.isA;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.greaterThanOrEqualTo;
-import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
@@ -67,8 +66,6 @@ import java.util.concurrent.TimeUnit;
 import java.util.concurrent.TimeoutException;
 import java.util.concurrent.atomic.AtomicBoolean;
 
-import com.amazonaws.ClientConfiguration;
-import com.amazonaws.client.builder.AwsClientBuilder;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.hamcrest.Condition;
@@ -80,13 +77,17 @@ import org.junit.Assert;
 import org.junit.Before;
 import org.junit.Test;
 import org.junit.runner.RunWith;
+import org.mockito.ArgumentCaptor;
 import org.mockito.Matchers;
 import org.mockito.Mock;
 import org.mockito.invocation.InvocationOnMock;
 import org.mockito.runners.MockitoJUnitRunner;
 import org.mockito.stubbing.Answer;
 
+import com.amazonaws.ClientConfiguration;
+import com.amazonaws.client.builder.AwsClientBuilder;
 import com.amazonaws.regions.RegionUtils;
+import com.amazonaws.regions.Regions;
 import com.amazonaws.services.cloudwatch.AmazonCloudWatch;
 import com.amazonaws.services.cloudwatch.AmazonCloudWatchClientBuilder;
 import com.amazonaws.services.dynamodbv2.AmazonDynamoDB;
@@ -1646,7 +1647,7 @@ public class WorkerTest {
         IRecordProcessorFactory recordProcessorFactory = mock(IRecordProcessorFactory.class);
         final String endpoint = "TestEndpoint";
         KinesisClientLibConfiguration config = new KinesisClientLibConfiguration("TestApp", null, null, null)
-                .withRegionName("us-west-2")
+                .withRegionName(Regions.US_WEST_2.getName())
                 .withKinesisEndpoint(endpoint)
                 .withDynamoDBEndpoint(endpoint);
 
@@ -1672,7 +1673,7 @@ public class WorkerTest {
     @Test
     public void testBuilderSetRegionToClient() {
         IRecordProcessorFactory recordProcessorFactory = mock(IRecordProcessorFactory.class);
-        String region = "us-west-2";
+        String region = Regions.US_WEST_2.getName();
         KinesisClientLibConfiguration config = new KinesisClientLibConfiguration("TestApp", null, null, null)
                 .withRegionName(region);
 
@@ -1702,6 +1703,7 @@ public class WorkerTest {
         IRecordProcessorFactory recordProcessorFactory = mock(IRecordProcessorFactory.class);
         KinesisClientLibConfiguration config = new KinesisClientLibConfiguration("TestApp", null, null, null);
         Worker.Builder builder = spy(new Worker.Builder().recordProcessorFactory(recordProcessorFactory).config(config));
+        ArgumentCaptor<AwsClientBuilder> builderCaptor = ArgumentCaptor.forClass(AwsClientBuilder.class);
 
         assertNull(builder.getKinesisClient());
         assertNull(builder.getDynamoDBClient());
@@ -1714,28 +1716,36 @@ public class WorkerTest {
         assertTrue(builder.getCloudWatchClient() instanceof AmazonCloudWatch);
 
         verify(builder, times(3)).createClient(
-                any(AwsClientBuilder.class), eq(null), any(ClientConfiguration.class), eq(null), eq(null));
+                builderCaptor.capture(), eq(null), any(ClientConfiguration.class), eq(null), eq(null));
+
+        builderCaptor.getAllValues().forEach(clientBuilder -> {
+            assertTrue(clientBuilder.getRegion().equals(Regions.US_EAST_1.getName()));
+        });
     }
 
     @Test
     public void testBuilderGenerateClientsWithRegion() {
         IRecordProcessorFactory recordProcessorFactory = mock(IRecordProcessorFactory.class);
-        String region = "us-west-2";
+        String region = Regions.US_WEST_2.getName();
         KinesisClientLibConfiguration config = new KinesisClientLibConfiguration("TestApp", null, null, null)
                 .withRegionName(region);
+        ArgumentCaptor<AwsClientBuilder> builderCaptor = ArgumentCaptor.forClass(AwsClientBuilder.class);
 
         Worker.Builder builder = spy(new Worker.Builder());
 
         builder.recordProcessorFactory(recordProcessorFactory).config(config).build();
 
         verify(builder, times(3)).createClient(
-                any(AwsClientBuilder.class), eq(null), any(ClientConfiguration.class), eq(null), eq(region));
+                builderCaptor.capture(), eq(null), any(ClientConfiguration.class), eq(null), eq(region));
+        builderCaptor.getAllValues().forEach(clientBuilder -> {
+            assertTrue(clientBuilder.getRegion().equals(region));
+        });
     }
 
     @Test
     public void testBuilderGenerateClientsWithEndpoint() {
         IRecordProcessorFactory recordProcessorFactory = mock(IRecordProcessorFactory.class);
-        String region = "us-west-2";
+        String region = Regions.US_WEST_2.getName();
         String endpointUrl = "TestEndpoint";
         KinesisClientLibConfiguration config = new KinesisClientLibConfiguration("TestApp", null, null, null)
                 .withRegionName(region).withKinesisEndpoint(endpointUrl).withDynamoDBEndpoint(endpointUrl);