diff --git a/src/main/java/org/gaul/s3proxy/S3ProxyHandler.java b/src/main/java/org/gaul/s3proxy/S3ProxyHandler.java
index 029cc24..af5268e 100644
--- a/src/main/java/org/gaul/s3proxy/S3ProxyHandler.java
+++ b/src/main/java/org/gaul/s3proxy/S3ProxyHandler.java
@@ -1458,7 +1458,8 @@ final class S3ProxyHandler extends AbstractHandler {
 
             MultipartPart part = blobStore.uploadMultipartPart(mpu, partNumber,
                     payload);
-            response.addHeader(HttpHeaders.ETAG, part.partETag());
+            response.addHeader(HttpHeaders.ETAG,
+                    "\"" + part.partETag() + "\"");
         }
     }