diff --git a/cotisations/migrations/0050_auto_20201102_2342.py b/cotisations/migrations/0050_auto_20201102_2342.py
new file mode 100644
index 00000000..9ab58611
--- /dev/null
+++ b/cotisations/migrations/0050_auto_20201102_2342.py
@@ -0,0 +1,40 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.29 on 2020-11-02 22:42
+from __future__ import unicode_literals
+
+import django.core.validators
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('cotisations', '0049_auto_20201102_2305'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='article',
+            name='duration_connection',
+            field=models.PositiveIntegerField(default=0, validators=[django.core.validators.MinValueValidator(0)], verbose_name='duration of the connection (in months)'),
+            preserve_default=False,
+        ),
+        migrations.AlterField(
+            model_name='article',
+            name='duration_days_connection',
+            field=models.PositiveIntegerField(default=0, validators=[django.core.validators.MinValueValidator(0)], verbose_name='duration of the connection (in days, will be added to duration in months)'),
+            preserve_default=False,
+        ),
+        migrations.AlterField(
+            model_name='article',
+            name='duration_days_membership',
+            field=models.PositiveIntegerField(default=0, validators=[django.core.validators.MinValueValidator(0)], verbose_name='duration of the membership (in days, will be added to duration in months)'),
+            preserve_default=False,
+        ),
+        migrations.AlterField(
+            model_name='article',
+            name='duration_membership',
+            field=models.PositiveIntegerField(default=0, validators=[django.core.validators.MinValueValidator(0)], verbose_name='duration of the membership (in months)'),
+            preserve_default=False,
+        ),
+    ]
diff --git a/cotisations/models.py b/cotisations/models.py
index ac75760b..4963e0ad 100644
--- a/cotisations/models.py
+++ b/cotisations/models.py
@@ -704,26 +704,18 @@ class Article(RevMixin, AclMixin, models.Model):
     )
 
     duration_membership = models.PositiveIntegerField(
-        blank=True,
-        null=True,
         validators=[MinValueValidator(0)],
         verbose_name=_("duration of the membership (in months)")
     )
     duration_days_membership = models.PositiveIntegerField(
-        blank=True,
-        null=True,
         validators=[MinValueValidator(0)],
         verbose_name=_("duration of the membership (in days, will be added to duration in months)"),
     )
     duration_connection = models.PositiveIntegerField(
-        blank=True,
-        null=True,
         validators=[MinValueValidator(0)],
         verbose_name=_("duration of the connection (in months)")
     )
     duration_days_connection = models.PositiveIntegerField(
-        blank=True,
-        null=True,
         validators=[MinValueValidator(0)],
         verbose_name=_("duration of the connection (in days, will be added to duration in months)"),
     )