diff --git a/tests/models.py b/tests/models.py
index c5b9c352..886e566f 100644
--- a/tests/models.py
+++ b/tests/models.py
@@ -339,7 +339,13 @@ class NoProfileChild(AbsNoProfile):
     pass
 
 
-class Mess(Post, Category):
+class ParentId(models.Model):
+    pass
+
+class ParentStr(models.Model):
+    name = models.CharField(max_length=128, primary_key=True)
+
+class Mess(ParentId, ParentStr):
     pass
 
 class MessChild(Mess):
diff --git a/tests/test_extras.py b/tests/test_extras.py
index 04afb9fa..7efde394 100644
--- a/tests/test_extras.py
+++ b/tests/test_extras.py
@@ -188,7 +188,8 @@ def test_db_agnostic_disabled(self):
 def test_model_family():
     from cacheops.utils import model_family
     from .models import Abs, Concrete1, AbsChild, Concrete2
-    from .models import NoProfile, NoProfileProxy, AbsNoProfile, NoProfileChild, Mess, MessChild
+    from .models import NoProfile, NoProfileProxy, AbsNoProfile, NoProfileChild
+    from .models import ParentId, ParentStr, Mess, MessChild
 
     # Abstract models do not have family, children of an abstract model are not a family
     assert model_family(Abs) == set()
@@ -203,4 +204,4 @@ def test_model_family():
     assert model_family(NoProfileChild) == {NoProfile, NoProfileProxy, NoProfileChild}
 
     # The worst of multiple inheritance
-    assert model_family(Mess) == {Mess, MessChild, Post, Category}
+    assert model_family(Mess) == {Mess, MessChild, ParentId, ParentStr}