diff --git a/addons/account/models/account_invoice.py b/addons/account/models/account_invoice.py
index 93951e68904..83a4c015179 100644
--- a/addons/account/models/account_invoice.py
+++ b/addons/account/models/account_invoice.py
@@ -1316,9 +1316,6 @@ class AccountInvoiceLine(models.Model):
                 self.price_unit = 0.0
             domain['uom_id'] = []
         else:
-            # Use the purchase uom by default
-            self.uom_id = self.product_id.uom_po_id
-
             if part.lang:
                 product = self.product_id.with_context(lang=part.lang)
             else:
diff --git a/addons/purchase/models/account_invoice.py b/addons/purchase/models/account_invoice.py
index 0aed9c09c26..43ffb17dddf 100644
--- a/addons/purchase/models/account_invoice.py
+++ b/addons/purchase/models/account_invoice.py
@@ -59,6 +59,13 @@ class AccountInvoice(models.Model):
             data['account_id'] = account.id
         return data
 
+    def _onchange_product_id(self):
+        domain = super(AccountInvoice, self)._onchange_product_id()
+        if self.purchase_id:
+            # Use the purchase uom by default
+            self.uom_id = self.product_id.uom_po_id
+        return domain
+
     # Load all unsold PO lines
     @api.onchange('purchase_id')
     def purchase_order_change(self):