diff --git a/model_utils/managers.py b/model_utils/managers.py
index 5a6ea68a..58c14edb 100644
--- a/model_utils/managers.py
+++ b/model_utils/managers.py
@@ -7,6 +7,7 @@
 from django.db import connection, models
 from django.db.models.constants import LOOKUP_SEP
 from django.db.models.fields.related import OneToOneField, OneToOneRel
+from django.db.models.query import ModelIterable, QuerySet
 from django.db.models.sql.datastructures import Join
 
 ModelT = TypeVar('ModelT', bound=models.Model, covariant=True)
@@ -16,45 +17,52 @@
     from typing import Any
 
     from django.db.models.query import BaseIterable
-    from django.db.models.query import ModelIterable as ModelIterableGeneric
-    from django.db.models.query import QuerySet as QuerySetGeneric
     from django.db.models.sql.query import Query
 
-    ModelIterable = ModelIterableGeneric[ModelT]
-    QuerySet = QuerySetGeneric[ModelT]
-else:
-    from django.db.models.query import ModelIterable, QuerySet
-
-
-class InheritanceIterable(ModelIterable):
-    def __iter__(self) -> Iterator[ModelT]:
-        queryset = self.queryset
-        iter: Iterable[ModelT] = ModelIterable(queryset)
-        if hasattr(queryset, 'subclasses'):
-            extras = tuple(queryset.query.extra.keys())
-            # sort the subclass names longest first,
-            # so with 'a' and 'a__b' it goes as deep as possible
-            subclasses = sorted(queryset.subclasses, key=len, reverse=True)
-            for obj in iter:
-                sub_obj = None
-                for s in subclasses:
-                    assert hasattr(queryset, '_get_sub_obj_recurse')
-                    sub_obj = queryset._get_sub_obj_recurse(obj, s)
-                    if sub_obj:
-                        break
-                if not sub_obj:
-                    sub_obj = obj
-
-                if hasattr(queryset, '_annotated'):
-                    for k in queryset._annotated:
-                        setattr(sub_obj, k, getattr(obj, k))
-
-                for k in extras:
+
+def _iter_inheritance_queryset(queryset: QuerySet[ModelT]) -> Iterator[ModelT]:
+    iter: Iterable[ModelT] = ModelIterable(queryset)
+    if hasattr(queryset, 'subclasses'):
+        extras = tuple(queryset.query.extra.keys())
+        # sort the subclass names longest first,
+        # so with 'a' and 'a__b' it goes as deep as possible
+        subclasses = sorted(queryset.subclasses, key=len, reverse=True)
+        for obj in iter:
+            sub_obj = None
+            for s in subclasses:
+                assert hasattr(queryset, '_get_sub_obj_recurse')
+                sub_obj = queryset._get_sub_obj_recurse(obj, s)
+                if sub_obj:
+                    break
+            if not sub_obj:
+                sub_obj = obj
+
+            if hasattr(queryset, '_annotated'):
+                for k in queryset._annotated:
                     setattr(sub_obj, k, getattr(obj, k))
 
-                yield sub_obj
-        else:
-            yield from iter
+            for k in extras:
+                setattr(sub_obj, k, getattr(obj, k))
+
+            yield sub_obj
+    else:
+        yield from iter
+
+
+if TYPE_CHECKING:
+    class InheritanceIterable(ModelIterable[ModelT]):
+        queryset: QuerySet[ModelT]
+
+        def __init__(self, queryset: QuerySet[ModelT], *args: Any, **kwargs: Any):
+            ...
+
+        def __iter__(self) -> Iterator[ModelT]:
+            ...
+
+else:
+    class InheritanceIterable(ModelIterable):
+        def __iter__(self):
+            return _iter_inheritance_queryset(self.queryset)
 
 
 class InheritanceQuerySetMixin(Generic[ModelT]):