diff --git a/3-binary-data/lib/images.js b/3-binary-data/lib/images.js
index 275418be97..2afb618025 100644
--- a/3-binary-data/lib/images.js
+++ b/3-binary-data/lib/images.js
@@ -44,7 +44,12 @@ function sendUploadToGCS (req, res, next) {
 
   var gcsname = Date.now() + req.file.originalname;
   var file = bucket.file(gcsname);
-  var stream = file.createWriteStream();
+
+  var stream = file.createWriteStream({
+    metadata: {
+      contentType: req.file.mimetype
+    }
+  });
 
   stream.on('error', function (err) {
     req.file.cloudStorageError = err;