diff --git a/data/processors/areatree/config.areatree b/data/processors/areatree/config.areatree
index d8546bbe5..d836db9b8 100644
--- a/data/processors/areatree/config.areatree
+++ b/data/processors/areatree/config.areatree
@@ -463,7 +463,7 @@
       5142:Parkhaus P1:
       -5143:Versorgungsstation:
       5160:UCN-Testanlage (Container):
-    :Max-Planck-Institut Garching:mpg[site],mpi # manually added, see NAT merger
+    :Max-Planck-Institut Garching:mpi,mpg[site] # manually added, see NAT merger
       :Max-Planck-Institut für Plasmaphysik:ipp[building]
       :Max-Planck-Institut für Astrophysik:mpa[building]
       :Max-Planck-Institut für Biochemie:mpb[building]
diff --git a/data/processors/areatree/process.py b/data/processors/areatree/process.py
index 8daab14b5..f5db28c6c 100644
--- a/data/processors/areatree/process.py
+++ b/data/processors/areatree/process.py
@@ -90,6 +90,10 @@ def _extract_id_and_type(internal_id: str, b_prefix: str | list[str] | None) ->
     results: models.IdType = {"id": "", "type": ""}
     if "[" in internal_id:
         internal_id, results["type"] = internal_id.removesuffix("]").split("[")
+        if "," in results["type"]:
+            raise RuntimeError(f"can't parse {internal_id}."
+                               f"The type has to be specified after specifying visible_ids."
+                               f"try :id,visible_ids[type] instead")
     if "," in internal_id:
         ids = internal_id.split(",")
         if len(ids) != 2:
diff --git a/data/processors/areatree/test_areatree.py b/data/processors/areatree/test_areatree.py
index b39936d51..9ef3a11d7 100644
--- a/data/processors/areatree/test_areatree.py
+++ b/data/processors/areatree/test_areatree.py
@@ -82,6 +82,16 @@ def test_specified_type() -> None:
     assert _extract_id_and_type("abc[building]", "cdf") == expected
 
 
+def test_comma_specified_type() -> None:
+    """If the building id is separated by a comma, it is split into a list"""
+
+    expected = {"id": "abc", "type": "building", 'visible_id': 'bcd'}
+    with pytest.raises(RuntimeError):
+        assert _extract_id_and_type("abc[building],bcd", None)
+    assert _extract_id_and_type("abc,bcd[building]", None) == expected
+    assert _extract_id_and_type("abc,bcd[building]", "cdf") == expected
+
+
 def test_comma() -> None:
     """If the id is inferable from the line, it is returned"""
     expected = {"id": "123", "visible_id": "visible_id", "type": "area"}
diff --git a/data/processors/nat.py b/data/processors/nat.py
index 6b7e436df..f9e96e190 100644
--- a/data/processors/nat.py
+++ b/data/processors/nat.py
@@ -58,6 +58,8 @@ def _infer_internal_id(building, data):
     if building.b_code.startswith("X"):
         if building.b_code == "XUCL":
             building.b_id = "origins-cluster"
+        elif building.b_code == "XMPG":
+            building.b_id = "mpi"
         else:
             building.b_id = building.b_code[1:].lower()