diff --git a/account_banking_mandate/models/account_banking_mandate.py b/account_banking_mandate/models/account_banking_mandate.py
index 5156d7de2..8e4ea65d0 100644
--- a/account_banking_mandate/models/account_banking_mandate.py
+++ b/account_banking_mandate/models/account_banking_mandate.py
@@ -71,33 +71,38 @@ class AccountBankingMandate(models.Model):
         'unique(unique_mandate_reference, company_id)',
         'A Mandate with the same reference already exists for this company !')]
 
-    @api.one
+    @api.multi
     @api.constrains('signature_date', 'last_debit_date')
     def _check_dates(self):
-        if (self.signature_date and
-                self.signature_date > fields.Date.context_today(self)):
-            raise exceptions.Warning(
-                _("The date of signature of mandate '%s' is in the future !")
-                % self.unique_mandate_reference)
-        if (self.signature_date and self.last_debit_date and
-                self.signature_date > self.last_debit_date):
-            raise exceptions.Warning(
-                _("The mandate '%s' can't have a date of last debit before "
-                  "the date of signature.") % self.unique_mandate_reference)
+        for mandate in self:
+            if (mandate.signature_date and
+                        mandate.signature_date > fields.Date.context_today(
+                        mandate)):
+                raise exceptions.Warning(
+                    _("The date of signature of mandate '%s' "
+                      "is in the future !")
+                    % mandate.unique_mandate_reference)
+            if (mandate.signature_date and mandate.last_debit_date and
+                        mandate.signature_date > mandate.last_debit_date):
+                raise exceptions.Warning(
+                    _("The mandate '%s' can't have a date of last debit "
+                      "before the date of signature."
+                      ) % mandate.unique_mandate_reference)
 
-    @api.one
+    @api.multi
     @api.constrains('state', 'partner_bank_id')
     def _check_valid_state(self):
-        if self.state == 'valid':
-            if not self.signature_date:
-                raise exceptions.Warning(
-                    _("Cannot validate the mandate '%s' without a date of "
-                      "signature.") % self.unique_mandate_reference)
-            if not self.partner_bank_id:
-                raise exceptions.Warning(
-                    _("Cannot validate the mandate '%s' because it is not "
-                      "attached to a bank account.") %
-                    self.unique_mandate_reference)
+        for mandate in self:
+            if mandate.state == 'valid':
+                if not mandate.signature_date:
+                    raise exceptions.Warning(
+                        _("Cannot validate the mandate '%s' without a date of "
+                          "signature.") % mandate.unique_mandate_reference)
+                if not mandate.partner_bank_id:
+                    raise exceptions.Warning(
+                        _("Cannot validate the mandate '%s' because it is not "
+                          "attached to a bank account.") %
+                        mandate.unique_mandate_reference)
 
     @api.model
     def create(self, vals=None):
@@ -106,10 +111,11 @@ class AccountBankingMandate(models.Model):
                 self.env['ir.sequence'].next_by_code('account.banking.mandate')
         return super(AccountBankingMandate, self).create(vals)
 
-    @api.one
+    @api.multi
     @api.onchange('partner_bank_id')
     def mandate_partner_bank_change(self):
-        self.partner_id = self.partner_bank_id.partner_id
+        for mandate in self:
+            mandate.partner_id = mandate.partner_bank_id.partner_id
 
     @api.multi
     def validate(self):