diff --git a/umap/migrations/0020_alter_tilelayer_url_template.py b/umap/migrations/0020_alter_tilelayer_url_template.py
new file mode 100644
index 00000000..75d77974
--- /dev/null
+++ b/umap/migrations/0020_alter_tilelayer_url_template.py
@@ -0,0 +1,19 @@
+# Generated by Django 5.0.2 on 2024-04-17 09:18
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    dependencies = [
+        ("umap", "0019_migrate_internal_remote_datalayers"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="tilelayer",
+            name="url_template",
+            field=models.CharField(
+                help_text="URL template using OSM tile format", max_length=400
+            ),
+        ),
+    ]
diff --git a/umap/models.py b/umap/models.py
index 6cd032ae..a8de01dc 100644
--- a/umap/models.py
+++ b/umap/models.py
@@ -92,7 +92,7 @@ class Licence(NamedModel):
 
 class TileLayer(NamedModel):
     url_template = models.CharField(
-        max_length=200, help_text=_("URL template using OSM tile format")
+        max_length=400, help_text=_("URL template using OSM tile format")
     )
     minZoom = models.IntegerField(default=0)
     maxZoom = models.IntegerField(default=18)