diff --git a/src/main/java/org/gaul/s3proxy/S3ProxyHandler.java b/src/main/java/org/gaul/s3proxy/S3ProxyHandler.java
index 829da07..6446a22 100644
--- a/src/main/java/org/gaul/s3proxy/S3ProxyHandler.java
+++ b/src/main/java/org/gaul/s3proxy/S3ProxyHandler.java
@@ -792,6 +792,14 @@ final class S3ProxyHandler extends AbstractHandler {
             return;
         }
 
+        // TODO: how to handle XML ACLs?
+        try (InputStream is = request.getInputStream()) {
+            int ch = is.read();
+            if (ch != -1) {
+                throw new S3Exception(S3ErrorCode.NOT_IMPLEMENTED);
+            }
+        }
+
         blobStore.setBlobAccess(containerName, blobName, access);
     }
 
diff --git a/src/test/java/org/gaul/s3proxy/S3AwsSdkTest.java b/src/test/java/org/gaul/s3proxy/S3AwsSdkTest.java
index 5417f29..26cc710 100644
--- a/src/test/java/org/gaul/s3proxy/S3AwsSdkTest.java
+++ b/src/test/java/org/gaul/s3proxy/S3AwsSdkTest.java
@@ -44,6 +44,7 @@ import com.amazonaws.SDKGlobalConfiguration;
 import com.amazonaws.auth.BasicAWSCredentials;
 import com.amazonaws.services.s3.AmazonS3;
 import com.amazonaws.services.s3.AmazonS3Client;
+import com.amazonaws.services.s3.model.AccessControlList;
 import com.amazonaws.services.s3.model.AmazonS3Exception;
 import com.amazonaws.services.s3.model.CompleteMultipartUploadRequest;
 import com.amazonaws.services.s3.model.CompleteMultipartUploadResult;
@@ -54,6 +55,7 @@ import com.amazonaws.services.s3.model.GetObjectRequest;
 import com.amazonaws.services.s3.model.InitiateMultipartUploadRequest;
 import com.amazonaws.services.s3.model.InitiateMultipartUploadResult;
 import com.amazonaws.services.s3.model.ObjectMetadata;
+import com.amazonaws.services.s3.model.Owner;
 import com.amazonaws.services.s3.model.PartETag;
 import com.amazonaws.services.s3.model.S3Object;
 import com.amazonaws.services.s3.model.UploadPartRequest;
@@ -294,6 +296,32 @@ public final class S3AwsSdkTest {
         }
     }
 
+    @Test
+    public void testUpdateBlobXmlAcls() throws Exception {
+        AmazonS3 client = new AmazonS3Client(awsCreds,
+                new ClientConfiguration().withSignerOverride("S3SignerType"));
+        client.setEndpoint(s3Endpoint.toString());
+
+        String blobName = "testUpdateBlobXmlAcls-blob";
+        ObjectMetadata metadata = new ObjectMetadata();
+        metadata.setContentLength(BYTE_SOURCE.size());
+        client.putObject(containerName, blobName, BYTE_SOURCE.openStream(),
+                metadata);
+
+        AccessControlList acl = new AccessControlList();
+        Owner owner = new Owner();
+        owner.setId("id");
+        owner.setDisplayName("display-name");
+        acl.setOwner(owner);
+
+        try {
+            client.setObjectAcl(containerName, blobName, acl);
+            Fail.failBecauseExceptionWasNotThrown(AmazonS3Exception.class);
+        } catch (AmazonS3Exception e) {
+            assertThat(e.getErrorCode()).isEqualTo("NotImplemented");
+        }
+    }
+
     private static final class NullX509TrustManager
             implements X509TrustManager {
         @Override