diff --git a/src/backend/InvenTree/InvenTree/models.py b/src/backend/InvenTree/InvenTree/models.py
index 5301141881..c8e8eb4ecf 100644
--- a/src/backend/InvenTree/InvenTree/models.py
+++ b/src/backend/InvenTree/InvenTree/models.py
@@ -451,7 +451,17 @@ class ReferenceIndexingMixin(models.Model):
     reference_int = models.BigIntegerField(default=0)
 
 
-class InvenTreeModel(PluginValidationMixin, models.Model):
+class ContentTypeMixin:
+    """Mixin class which supports retrieval of the ContentType for a model instance."""
+
+    def get_content_type(self):
+        """Return the ContentType object associated with this model."""
+        from django.contrib.contenttypes.models import ContentType
+
+        return ContentType.objects.get_for_model(self.__class__)
+
+
+class InvenTreeModel(ContentTypeMixin, PluginValidationMixin, models.Model):
     """Base class for InvenTree models, which provides some common functionality.
 
     Includes the following mixins by default:
@@ -658,7 +668,7 @@ class InvenTreeAttachmentMixin(InvenTreePermissionCheckMixin):
         Attachment.objects.create(**kwargs)
 
 
-class InvenTreeTree(MPTTModel):
+class InvenTreeTree(ContentTypeMixin, MPTTModel):
     """Provides an abstracted self-referencing tree model, based on the MPTTModel class.
 
     Our implementation provides the following key improvements:
diff --git a/src/backend/InvenTree/part/test_param.py b/src/backend/InvenTree/part/test_param.py
index 4e3bae3a70..c1a536bc25 100644
--- a/src/backend/InvenTree/part/test_param.py
+++ b/src/backend/InvenTree/part/test_param.py
@@ -369,13 +369,21 @@ class PartParameterTest(InvenTreeAPITestCase):
 
         # test that having non unique part/template combinations fails
         res = self.post(url, data, expected_code=400)
+
         self.assertEqual(len(res.data), 3)
         self.assertEqual(len(res.data[1]), 0)
         for err in [res.data[0], res.data[2]]:
-            self.assertEqual(len(err), 2)
+            self.assertEqual(len(err), 3)
             self.assertEqual(str(err['model_id'][0]), 'This field must be unique.')
+            self.assertEqual(str(err['model_type'][0]), 'This field must be unique.')
             self.assertEqual(str(err['template'][0]), 'This field must be unique.')
-        self.assertEqual(Parameter.objects.filter(content_object=part4).count(), 0)
+
+        self.assertEqual(
+            Parameter.objects.filter(
+                model_type=part4.get_content_type(), model_id=part4.pk
+            ).count(),
+            0,
+        )
 
         # Now, create a valid set of parameters
         data = [
@@ -384,7 +392,13 @@ class PartParameterTest(InvenTreeAPITestCase):
         ]
         res = self.post(url, data, expected_code=201)
         self.assertEqual(len(res.data), 2)
-        self.assertEqual(Parameter.objects.filter(content_object=part4).count(), 2)
+
+        self.assertEqual(
+            Parameter.objects.filter(
+                model_type=part4.get_content_type(), model_id=part4.pk
+            ).count(),
+            2,
+        )
 
     def test_param_detail(self):
         """Tests for the Parameter detail endpoint."""