diff --git a/lib/gridfs-stream/upload.js b/lib/gridfs-stream/upload.js
index 40e1eab3ff..578949a53d 100644
--- a/lib/gridfs-stream/upload.js
+++ b/lib/gridfs-stream/upload.js
@@ -422,7 +422,7 @@ function doWrite(_this, chunk, encoding, callback) {
       if (_this.md5) {
         _this.md5.update(_this.bufToStore);
       }
-      var doc = createChunkDoc(_this.id, _this.n, _this.bufToStore);
+      var doc = createChunkDoc(_this.id, _this.n, Buffer.from(_this.bufToStore));
       ++_this.state.outstandingRequests;
       ++outstandingRequests;