diff --git a/src/openforms/config/tests/factories.py b/src/openforms/config/tests/factories.py
index 08476e714b..745819c796 100644
--- a/src/openforms/config/tests/factories.py
+++ b/src/openforms/config/tests/factories.py
@@ -17,7 +17,7 @@ class Meta:
 
 
 class MapTileLayerFactory(factory.django.DjangoModelFactory):
-    identifier = factory.Faker("word")
+    identifier = factory.Sequence(lambda n: f"map-tile-layer-{n}")
     url = factory.Sequence(lambda n: f"http://example-{n}.com")
     label = factory.Faker("word")