diff --git a/src/main/java/software/amazon/awssdk/s3accessgrants/plugin/S3AccessGrantsPlugin.java b/src/main/java/software/amazon/awssdk/s3accessgrants/plugin/S3AccessGrantsPlugin.java
index 77e61bb..6586e11 100644
--- a/src/main/java/software/amazon/awssdk/s3accessgrants/plugin/S3AccessGrantsPlugin.java
+++ b/src/main/java/software/amazon/awssdk/s3accessgrants/plugin/S3AccessGrantsPlugin.java
@@ -72,9 +72,6 @@ String userAgent() {
         return this.userAgent;
     }
 
-    ClientOverrideConfiguration overrideConfig = ClientOverrideConfiguration.builder()
-                    .putAdvancedOption(SdkAdvancedClientOption.USER_AGENT_PREFIX, userAgent()).build();
-
     /**
      * Change the configuration on the S3Clients to use S3 Access Grants specific AuthScheme and identityProviders.
      * @param config the existing configuration on the clients. Passed by the SDK on request path.
@@ -103,6 +100,9 @@ public void configureClient(SdkServiceClientConfiguration.Builder config) {
         S3ControlAsyncClientBuilder s3ControlAsyncClientBuilder = S3ControlAsyncClient.builder()
                 .credentialsProvider(serviceClientConfiguration.credentialsProvider());
 
+        ClientOverrideConfiguration overrideConfig = ClientOverrideConfiguration.builder()
+            .putAdvancedOption(SdkAdvancedClientOption.USER_AGENT_PREFIX, userAgent()).build();
+
         S3Client s3Client = S3Client
                 .builder()
                 .crossRegionAccessEnabled(true)
diff --git a/src/test/java/software/amazon/awssdk/s3accessgrants/plugin/S3AccessGrantsPluginTests.java b/src/test/java/software/amazon/awssdk/s3accessgrants/plugin/S3AccessGrantsPluginTests.java
index 933d11f..9e170cb 100644
--- a/src/test/java/software/amazon/awssdk/s3accessgrants/plugin/S3AccessGrantsPluginTests.java
+++ b/src/test/java/software/amazon/awssdk/s3accessgrants/plugin/S3AccessGrantsPluginTests.java
@@ -18,15 +18,24 @@
 import org.junit.BeforeClass;
 import org.junit.Test;
 import org.assertj.core.api.Assertions;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import software.amazon.awssdk.core.SdkServiceClientConfiguration;
 import software.amazon.awssdk.core.exception.SdkClientException;
 import software.amazon.awssdk.services.s3.S3ServiceClientConfiguration;
 import software.amazon.awssdk.services.s3.auth.scheme.S3AuthSchemeProvider;
 import software.amazon.awssdk.auth.credentials.DefaultCredentialsProvider;
 import software.amazon.awssdk.regions.Region;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
 
 public class S3AccessGrantsPluginTests {
 
+    private static final Logger logger = LoggerFactory.getLogger(S3AccessGrantsPluginTests.class);
+
     @BeforeClass
     public static void setUp() {
         System.setProperty("aws.region", "us-east-2");
@@ -156,4 +165,39 @@ public void create_access_grants_plugin_without_userAgent_specified() {
     public void create_access_grants_plugin_with_not_permitted_userAgent_name() {
         Assertions.assertThatThrownBy(() -> S3AccessGrantsPlugin.builder().userAgent("testUserAgent/").build()).isInstanceOf(IllegalArgumentException.class);
     }
+
+    @Test
+    public void configureClient_concurrent_access_should_not_throw_null_pointer_exception() throws InterruptedException {
+        S3AccessGrantsPlugin accessGrantsPlugin = S3AccessGrantsPlugin.builder().build();
+        int threadCount = 10;
+        ExecutorService executor = Executors.newFixedThreadPool(threadCount);
+        CountDownLatch latch = new CountDownLatch(threadCount);
+        AtomicInteger successCount = new AtomicInteger(0);
+        AtomicInteger exceptionCount = new AtomicInteger(0);
+
+        for (int i = 0; i < threadCount; i++) {
+            executor.submit(() -> {
+                try {
+                    SdkServiceClientConfiguration.Builder config = S3ServiceClientConfiguration.builder()
+                            .authSchemeProvider(S3AuthSchemeProvider.defaultProvider())
+                            .credentialsProvider(DefaultCredentialsProvider.create())
+                            .region(Region.US_EAST_2);
+                    
+                    accessGrantsPlugin.configureClient(config);
+                    successCount.incrementAndGet();
+                } catch (Exception e) {
+                    exceptionCount.incrementAndGet();
+                    logger.error("An error occurred: ", e);
+                } finally {
+                    latch.countDown();
+                }
+            });
+        }
+
+        latch.await(10, TimeUnit.SECONDS);
+        executor.shutdown();
+
+        Assertions.assertThat(successCount.get()).isEqualTo(threadCount);
+        Assertions.assertThat(exceptionCount.get()).isEqualTo(0);
+    }
 }