diff --git a/portingdb/htmlreport.py b/portingdb/htmlreport.py
index 5bb49a5eb8a..a25e80950f7 100644
--- a/portingdb/htmlreport.py
+++ b/portingdb/htmlreport.py
@@ -9,7 +9,7 @@
 import datetime
 
 from flask import Flask, render_template, current_app, Markup, abort, url_for
-from flask import make_response, request
+from flask import make_response, request, Response
 from flask.json import jsonify
 from sqlalchemy import func, and_, create_engine
 from sqlalchemy.orm import subqueryload, eagerload, sessionmaker, joinedload
@@ -568,7 +568,7 @@ def history_csv():
             'status': row.status,
             'num_packages': row.num_packages,
         })
-    return sio.getvalue()
+    return Response(sio.getvalue(), mimetype='text/csv')
 
 
 def group_by_loc(grp):
@@ -845,7 +845,7 @@ def history_naming_csv():
             'status': row.status,
             'num_packages': row.num_packages,
         })
-    return sio.getvalue()
+    return Response(sio.getvalue(), mimetype='text/csv')
 
 
 def format_quantity(num):