diff --git a/postgres_composite_types/composite_type.py b/postgres_composite_types/composite_type.py
index 49652f7..60bbae2 100644
--- a/postgres_composite_types/composite_type.py
+++ b/postgres_composite_types/composite_type.py
@@ -61,8 +61,7 @@ def __new__(cls, name, bases, attrs):
         # create the field for this Type
         attrs["Field"] = type(f"{name}.Field", (BaseField,), {})
 
-        attrs["__id"] = DummyField(primary_key=True, serialize=False)
-        attrs["__id"].name = "pk"
+        attrs[DummyField.name] = DummyField(primary_key=True, serialize=False)
 
         # Use an EmptyManager for everything as types cannot be queried.
         meta_obj.default_manager_name = "objects"
diff --git a/postgres_composite_types/fields.py b/postgres_composite_types/fields.py
index dbbdbb5..60f0479 100644
--- a/postgres_composite_types/fields.py
+++ b/postgres_composite_types/fields.py
@@ -16,6 +16,8 @@ class DummyField(Field):
     all models to have a primary key.
     """
 
+    name = "_id_not_used"
+
 
 class BaseField(Field):
     """Base class for the field that relates to this type."""
@@ -73,7 +75,7 @@ def to_python(self, value):
                 **{
                     field.name: field.to_python(value.get(field.name))
                     for field in self._composite_type_model._meta.fields
-                    if field.name != "pk"
+                    if field.name != DummyField.name
                 }
             )
 
@@ -89,6 +91,6 @@ def value_to_string(self, obj):
             {
                 field.name: field.value_to_string(value)
                 for field in self._composite_type_model._meta.fields
-                if field.name != "pk"
+                if field.name != DummyField.name
             }
         )
diff --git a/postgres_composite_types/forms.py b/postgres_composite_types/forms.py
index 6629b8e..d4ae85c 100644
--- a/postgres_composite_types/forms.py
+++ b/postgres_composite_types/forms.py
@@ -12,6 +12,7 @@
 from django.utils.translation import gettext as _
 
 from . import CompositeType
+from .fields import DummyField
 
 LOGGER = logging.getLogger(__name__)
 
@@ -64,7 +65,7 @@ def __init__(self, *args, fields=None, model=None, **kwargs):
         fields = {
             field.name: field.formfield()
             for field in fields or model._meta.fields
-            if field.name != "pk"
+            if field.name != DummyField.name
         }
 
         widget = CompositeTypeWidget(
diff --git a/postgres_composite_types/operations.py b/postgres_composite_types/operations.py
index b226097..a73309a 100644
--- a/postgres_composite_types/operations.py
+++ b/postgres_composite_types/operations.py
@@ -16,7 +16,7 @@ def sql_create_type(type_name, fields, schema_editor):
     fields_list = ", ".join(
         sql_field_definition(field_name, field, schema_editor)
         for field_name, field in fields
-        if field_name != "__id"
+        if field_name != DummyField.name
     )
     quoted_name = schema_editor.quote_name(type_name)
     return f"CREATE TYPE {quoted_name} AS ({fields_list})"
@@ -33,7 +33,10 @@ class CreateType(CreateModel):
     reversible = True
 
     def __init__(self, *, name: str, fields, options) -> None:
-        fields = [("__id", DummyField(primary_key=True, serialize=False)), *fields]
+        fields = [
+            (DummyField.name, DummyField(primary_key=True, serialize=False)),
+            *fields,
+        ]
         super().__init__(name, fields, options)
 
     def describe(self):
diff --git a/postgres_composite_types/quoting.py b/postgres_composite_types/quoting.py
index 23865fe..8571564 100644
--- a/postgres_composite_types/quoting.py
+++ b/postgres_composite_types/quoting.py
@@ -1,5 +1,7 @@
 from psycopg2.extensions import ISQLQuote, adapt
 
+from .fields import DummyField
+
 __all__ = ["QuotedCompositeType"]
 
 
@@ -23,7 +25,7 @@ def __init__(self, obj):
                     self.model.registered_connection,
                 )
                 for field in self.model._meta.fields
-                if field.name != "pk"
+                if field.name != DummyField.name
             )
         )