diff --git a/contract_recurring_invoicing_marker/models/account_analytic_account.py b/contract_recurring_invoicing_marker/models/account_analytic_account.py
index a134d75e..b4828584 100644
--- a/contract_recurring_invoicing_marker/models/account_analytic_account.py
+++ b/contract_recurring_invoicing_marker/models/account_analytic_account.py
@@ -24,6 +24,12 @@ class AccountAnalyticAccount(models.Model):
         obj = self.with_context(old_date=old_date, next_date=new_date)
         return super(AccountAnalyticAccount, obj)._prepare_invoice(contract)
 
+    @api.model
+    def _insert_markers(self, line, date_start, date_end, date_format):
+        line = line.replace('#START#', date_start.strftime(date_format))
+        line = line.replace('#END#', date_end.strftime(date_format))
+        return line
+
     @api.model
     def _prepare_invoice_line(self, line, invoice_id):
         res = super(AccountAnalyticAccount, self)._prepare_invoice_line(
@@ -34,8 +40,7 @@ class AccountAnalyticAccount(models.Model):
             lang = lang_obj.search(
                 [('code', '=', contract.partner_id.lang)])
             date_format = lang.date_format or '%d/%M/%Y'
-            res['name'] = res['name'].replace(
-                '#START#', self.env.context['old_date'].strftime(date_format))
-            res['name'] = res['name'].replace(
-                '#END#', self.env.context['next_date'].strftime(date_format))
+            res['name'] = self._insert_markers(
+                res['name'], self.env.context['old_date'],
+                self.env.context['next_date'], date_format)
         return res
diff --git a/contract_recurring_invoicing_marker/views/account_analytic_account_view.xml b/contract_recurring_invoicing_marker/views/account_analytic_account_view.xml
index 5bc87358..fbbd330b 100644
--- a/contract_recurring_invoicing_marker/views/account_analytic_account_view.xml
+++ b/contract_recurring_invoicing_marker/views/account_analytic_account_view.xml
@@ -8,7 +8,7 @@
             <field name="inherit_id" ref="account_analytic_analysis.account_analytic_account_form_form"/>
             <field name="arch" type="xml">
                 <field name="recurring_invoice_line_ids" position="after">
-                    <group string="Legend (for the markers inside invoice lines description)">
+                    <group string="Legend (for the markers inside invoice lines description)" name="group_legend">
                         <p colspan="2"> <strong>#START#</strong>: Start date of the invoiced period</p>
                         <p colspan="2"> <strong>#END#</strong>: End date of the invoiced period</p>
                     </group>