diff --git a/sophon/core/migrations/0003_auto_20210406_0044.py b/sophon/core/migrations/0003_auto_20210406_0044.py
new file mode 100644
index 0000000..ca4b218
--- /dev/null
+++ b/sophon/core/migrations/0003_auto_20210406_0044.py
@@ -0,0 +1,18 @@
+# Generated by Django 3.1.7 on 2021-04-06 00:44
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('core', '0002_auto_20210405_1641'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='project',
+            name='sources',
+            field=models.ManyToManyField(blank=True, help_text='The sources used by this project.', related_name='used_in', to='core.DataSource'),
+        ),
+    ]
diff --git a/sophon/core/models.py b/sophon/core/models.py
index 2f1ca18..93b9f75 100644
--- a/sophon/core/models.py
+++ b/sophon/core/models.py
@@ -56,7 +56,7 @@ class Project(models.Model):
         DataSource,
         help_text="The sources used by this project.",
         related_name="used_in",
-        null=True,
+        blank=True,
     )
 
     def __str__(self):