diff --git a/kfet/views.py b/kfet/views.py
index 7083d489..125ce9b1 100644
--- a/kfet/views.py
+++ b/kfet/views.py
@@ -963,7 +963,7 @@ def kpsul_perform_operations(request):
             if operationgroup.on_acc.is_cof:
                 if is_addcost:
                     operation.addcost_amount = operation.addcost_amount / cof_grant_divisor
-                operation.amount = operation.amount / cof_grant_divisor
+                operation.amount = Decimal(float(operation.amount) / cof_grant_divisor)
             to_articles_stocks[operation.article] -= operation.article_nb
         else:
             if operationgroup.on_acc.is_cash: