diff --git a/date_range/__init__.py b/date_range/__init__.py
index dcac9c0..faa4535 100644
--- a/date_range/__init__.py
+++ b/date_range/__init__.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # © 2016 ACSONE SA/NV (<http://acsone.eu>)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
diff --git a/date_range/__manifest__.py b/date_range/__manifest__.py
index 5922d3c..89d6b2b 100644
--- a/date_range/__manifest__.py
+++ b/date_range/__manifest__.py
@@ -1,10 +1,9 @@
-# -*- coding: utf-8 -*-
 # © 2016 ACSONE SA/NV (<http://acsone.eu>)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 {
     "name": "Date Range",
     "summary": "Manage all kind of date range",
-    "version": "11.0.1.0.0",
+    "version": "11.0.1.0.1",
     "category": "Uncategorized",
     "website": "https://github.com/oca/server-ux",
     "author": "ACSONE SA/NV, Odoo Community Association (OCA)",
diff --git a/date_range/models/__init__.py b/date_range/models/__init__.py
index feae177..2464998 100644
--- a/date_range/models/__init__.py
+++ b/date_range/models/__init__.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # © 2016 ACSONE SA/NV (<http://acsone.eu>)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
diff --git a/date_range/models/date_range.py b/date_range/models/date_range.py
index 92ba83f..4e60e39 100644
--- a/date_range/models/date_range.py
+++ b/date_range/models/date_range.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # © 2016 ACSONE SA/NV (<http://acsone.eu>)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
@@ -19,7 +18,8 @@ class DateRange(models.Model):
     date_start = fields.Date(string='Start date', required=True)
     date_end = fields.Date(string='End date', required=True)
     type_id = fields.Many2one(
-        comodel_name='date.range.type', string='Type', index=1, required=True)
+        comodel_name='date.range.type', string='Type', index=1, required=True,
+        ondelete='restrict')
     type_name = fields.Char(
         string='Type', related='type_id.name', readonly=True, store=True)
     company_id = fields.Many2one(
diff --git a/date_range/models/date_range_type.py b/date_range/models/date_range_type.py
index bff6e4f..d8414cf 100644
--- a/date_range/models/date_range_type.py
+++ b/date_range/models/date_range_type.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # © 2016 ACSONE SA/NV (<http://acsone.eu>)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
diff --git a/date_range/static/src/js/date_range.js b/date_range/static/src/js/date_range.js
index 673070f..7775f55 100644
--- a/date_range/static/src/js/date_range.js
+++ b/date_range/static/src/js/date_range.js
@@ -3,26 +3,25 @@
 odoo.define('date_range.search_filters', function (require) {
 "use strict";
 
-var core = require('web.core'); 
+var core = require('web.core');
 var data = require('web.data');
 var filters = require('web.search_filters');
 var rpc = require('web.rpc');
 var framework = require('web.framework');
 
 var _t = core._t;
-var _lt = core._lt;
 filters.ExtendedSearchProposition.include({
     select_field: function(field) {
         this._super.apply(this, arguments);
         this.is_date_range_selected = false;
-        this.is_date = field.type == 'date' || field.type == 'datetime';
+        this.is_date = field.type === 'date' || field.type === 'datetime';
         this.$value = this.$el.find('.searchview_extended_prop_value, .o_searchview_extended_prop_value');
         if (this.is_date){
             var ds = new data.DataSetSearch(this, 'date.range.type', this.context, [[1, '=', 1]]);
             ds.read_slice(['name'], {}).done(this.proxy('add_date_range_types_operator'));
         }
     },
-    
+
     add_date_range_types_operator: function(date_range_types){
         var self = this;
         _.each(date_range_types, function(drt) {
@@ -31,10 +30,10 @@ filters.ExtendedSearchProposition.include({
                 .appendTo(self.$el.find('.searchview_extended_prop_op, .o_searchview_extended_prop_op'));
         });
     },
-    
+
     operator_changed: function (e) {
         var val = $(e.target).val();
-        this.is_date_range_selected = val.startsWith('drt_'); 
+        this.is_date_range_selected = val.startsWith('drt_');
         if (this.is_date_range_selected){
             var type_id = val.replace('drt_', '');
             this.date_range_type_operator_selected(type_id);
@@ -47,18 +46,18 @@ filters.ExtendedSearchProposition.include({
         this.$value.empty().show();
         var ds = new data.DataSetSearch(this, 'date.range', this.context, [['type_id', '=', parseInt(type_id)]]);
         ds.read_slice(['name','date_start', 'date_end'], {}).done(this.proxy('on_range_type_selected'));
-            
+
     },
-    
+
     on_range_type_selected: function(date_range_values){
         this.value = new filters.ExtendedSearchProposition.DateRange(this, this.value.field, date_range_values);
         this.value.appendTo(this.$value);
         if (!this.$el.hasClass('o_filter_condition')){
-            this.$value.find('.date-range-select').addClass('form-control');   
+            this.$value.find('.date-range-select').addClass('form-control');
         }
         this.value.on_range_selected();
     },
-    
+
     get_filter: function () {
         var res = this._super.apply(this, arguments);
         if (this.is_date_range_selected){
@@ -68,7 +67,7 @@ filters.ExtendedSearchProposition.include({
         }
         return res;
     },
-    
+
 });
 
 /**
@@ -83,7 +82,7 @@ filters.ExtendedSearchProposition.DateRange = core.search_filters_registry.get('
     events: {
         'change': 'on_range_selected',
     },
-    
+
     init: function (parent, field, date_range_values) {
         this._super(parent, field);
         this.date_range_values = date_range_values;
@@ -94,11 +93,11 @@ filters.ExtendedSearchProposition.DateRange = core.search_filters_registry.get('
         var option = select.options[select.selectedIndex];
         return option.label || option.text;
     },
-    
+
     get_value: function() {
         return parseInt(this.$el.val());
     },
-    
+
     on_range_selected: function(e){
         var self = this;
         self.domain = '';
@@ -116,11 +115,11 @@ filters.ExtendedSearchProposition.DateRange = core.search_filters_registry.get('
                 self.domain = domain;
             });
     },
-    
+
     get_domain: function (field, operator) {
         return this.domain;
     },
 
 });
 
-});
\ No newline at end of file
+});
diff --git a/date_range/tests/__init__.py b/date_range/tests/__init__.py
index d4e3ce6..974619e 100644
--- a/date_range/tests/__init__.py
+++ b/date_range/tests/__init__.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # © 2016 ACSONE SA/NV (<http://acsone.eu>)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
diff --git a/date_range/tests/test_date_range.py b/date_range/tests/test_date_range.py
index c84b6c1..5431476 100644
--- a/date_range/tests/test_date_range.py
+++ b/date_range/tests/test_date_range.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # © 2016 ACSONE SA/NV (<http://acsone.eu>)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl)
 
diff --git a/date_range/tests/test_date_range_generator.py b/date_range/tests/test_date_range_generator.py
index 1c47c9d..04f7318 100644
--- a/date_range/tests/test_date_range_generator.py
+++ b/date_range/tests/test_date_range_generator.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # © 2016 ACSONE SA/NV (<http://acsone.eu>)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl)nses/agpl).
 
diff --git a/date_range/tests/test_date_range_type.py b/date_range/tests/test_date_range_type.py
index 0816267..37a03b3 100644
--- a/date_range/tests/test_date_range_type.py
+++ b/date_range/tests/test_date_range_type.py
@@ -1,8 +1,9 @@
-# -*- coding: utf-8 -*-
 # © 2016 ACSONE SA/NV (<http://acsone.eu>)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl)
 
 from odoo.tests.common import TransactionCase
+from odoo.tools import mute_logger
+from psycopg2 import IntegrityError
 
 
 class DateRangeTypeTest(TransactionCase):
@@ -18,3 +19,17 @@ class DateRangeTypeTest(TransactionCase):
              'company_id': False,
              'allow_overlap': False})
         self.assertFalse(drt.company_id)
+
+    def test_unlink(self):
+        date_range = self.env['date.range']
+        drt = self.env['date.range.type'].create(
+            {'name': 'Fiscal year',
+             'allow_overlap': False})
+        date_range.create({
+            'name': 'FS2016',
+            'date_start': '2015-01-01',
+            'date_end': '2016-12-31',
+            'type_id': drt.id,
+        })
+        with self.assertRaises(IntegrityError), mute_logger('odoo.sql_db'):
+            drt.unlink()
diff --git a/date_range/wizard/__init__.py b/date_range/wizard/__init__.py
index 2b52501..c9d4472 100644
--- a/date_range/wizard/__init__.py
+++ b/date_range/wizard/__init__.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # © 2016 ACSONE SA/NV (<http://acsone.eu>)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).
 
diff --git a/date_range/wizard/date_range_generator.py b/date_range/wizard/date_range_generator.py
index 2b61075..b4d3045 100644
--- a/date_range/wizard/date_range_generator.py
+++ b/date_range/wizard/date_range_generator.py
@@ -1,4 +1,3 @@
-# -*- coding: utf-8 -*-
 # © 2016 ACSONE SA/NV (<http://acsone.eu>)
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).