diff --git a/addons/l10n_fr_pos_cert/static/src/js/pos.js b/addons/l10n_fr_pos_cert/static/src/js/pos.js
index 502e5f98cf4b5342fb075a01549e5efaec815016..86dc047ed1449bc8097d1a6351f145337ffb6683 100644
--- a/addons/l10n_fr_pos_cert/static/src/js/pos.js
+++ b/addons/l10n_fr_pos_cert/static/src/js/pos.js
@@ -36,7 +36,7 @@ models.PosModel = models.PosModel.extend({
     },
 
     disallowLineQuantityChange() {
-        let result = _super_posmodel.disallowLineQuantityChange();
+        let result = _super_posmodel.disallowLineQuantityChange.bind(this)();
         return this.is_french_country() || result;
     }
 });