diff --git a/addons/website_event_sale/controllers/main.py b/addons/website_event_sale/controllers/main.py
index 67c7e0a3609..3f4a5e049a8 100644
--- a/addons/website_event_sale/controllers/main.py
+++ b/addons/website_event_sale/controllers/main.py
@@ -49,6 +49,7 @@ class website_event(website_event):
         for key, value in post.items():
             try:
                 quantity = int(value)
+                assert quantity > 0
             except:
                 quantity = None
             ticket_id = key.split("-")[0] == 'ticket' and int(key.split("-")[1]) or None