diff --git a/fractal_database_matrix/migrations/0001_initial.py b/fractal_database_matrix/migrations/0001_initial.py
index 48705d7..70d839d 100644
--- a/fractal_database_matrix/migrations/0001_initial.py
+++ b/fractal_database_matrix/migrations/0001_initial.py
@@ -1,4 +1,4 @@
-# Generated by Django 5.0.2 on 2024-02-16 22:59
+# Generated by Django 5.0.2 on 2024-02-22 21:00
 
 import django.db.models.deletion
 from django.db import migrations, models
diff --git a/fractal_database_matrix/representations.py b/fractal_database_matrix/representations.py
index e64e3ac..c6361bf 100644
--- a/fractal_database_matrix/representations.py
+++ b/fractal_database_matrix/representations.py
@@ -264,14 +264,26 @@ async def create_representation(self, repr_log: "RepresentationLog", target_id:
         """
         Creates a Matrix space for the ReplicatedModel "instance" that inherits from this class
         """
-        model_class = repr_log.content_type.model_class()
+        # get the model the object that this representation log is for
+        # (this is usually a ReplicationTarget model since only ReplicationTargets can create representations)
+        model_class: "MatrixReplicationTarget" = repr_log.content_type.model_class()  # type: ignore
+        # get the model for the target that this representation log is for
         target_model = repr_log.target_type.model_class()
+        # fetch the replicated model that this representation log is for
         instance = await model_class.objects.aget(pk=repr_log.object_id)
-        target = await target_model.objects.prefetch_related("matrixcredentials_set").aget(
+        # fetch the target
+        target: "MatrixReplicationTarget" = await target_model.objects.prefetch_related(
+            "matrixcredentials_set"
+        ).aget(
             pk=target_id
-        )
+        )  # type: ignore
+
+        # pull room ids from metadata
         parent_room_id = target.metadata["room_id"]
         child_room_id = instance.metadata["room_id"]
+        if parent_room_id == child_room_id:
+            raise Exception("Parent and child room IDs cannot be the same")
+
         await self.add_subspace(target, parent_room_id, child_room_id)