diff --git a/stock_reserve/model/stock_reserve.py b/stock_reserve/model/stock_reserve.py
index 145f37e52..aa5e08844 100644
--- a/stock_reserve/model/stock_reserve.py
+++ b/stock_reserve/model/stock_reserve.py
@@ -59,6 +59,17 @@ class StockReservation(models.Model):
         select=1)
     date_validity = fields.Date('Validity Date')
 
+    @api.model
+    def default_get(self, fields_list):
+        """
+        Ensure default value of computed field `product_qty` is not set
+        as it would raise an error
+        """
+        res = super(StockReservation, self).default_get(fields_list)
+        if 'product_qty' in res:
+            del res['product_qty']
+        return res
+
     @api.model
     def get_location_from_ref(self, ref):
         """ Get a location from a xmlid if allowed