diff --git a/services/filestore/app/js/FileController.js b/services/filestore/app/js/FileController.js
index 726438a557..eef441436c 100644
--- a/services/filestore/app/js/FileController.js
+++ b/services/filestore/app/js/FileController.js
@@ -62,6 +62,7 @@ function getFile(req, res, next) {
 
     logger.log({ key, bucket, format, style }, 'sending file to response')
 
+    // pass 'next' as a callback to 'pipeline' to receive any errors
     pipeline(fileStream, res, next)
   })
 }