diff --git a/sqlalchemy_file/helpers.py b/sqlalchemy_file/helpers.py
index 39ef3a0..021ca0d 100644
--- a/sqlalchemy_file/helpers.py
+++ b/sqlalchemy_file/helpers.py
@@ -4,7 +4,7 @@
 import re
 from builtins import RuntimeError
 from tempfile import SpooledTemporaryFile
-from typing import Any, Dict, Union
+from typing import Any, Dict, List, Union
 
 INMEMORY_FILESIZE = 1024 * 1024
 LOCAL_STORAGE_DRIVER_NAME = "Local Storage"
@@ -74,3 +74,8 @@ def convert_size(size: Union[str, int]) -> int:
         si_map = {"k": 1000, "K": 1000, "M": 1000**2, "Ki": 1024, "Mi": 1024**2}
         return int(value) * si_map[si]
     return size
+
+
+def flatmap(lists: List[List[Any]]) -> List[Any]:
+    """Flattens a list of lists into a single list."""
+    return [value for _list in lists for value in _list]
diff --git a/sqlalchemy_file/types.py b/sqlalchemy_file/types.py
index 9c97000..69fbb7e 100644
--- a/sqlalchemy_file/types.py
+++ b/sqlalchemy_file/types.py
@@ -5,6 +5,7 @@
 from sqlalchemy.orm import ColumnProperty, Mapper, Session, SessionTransaction
 from sqlalchemy.orm.attributes import get_history
 from sqlalchemy_file.file import File
+from sqlalchemy_file.helpers import flatmap
 from sqlalchemy_file.mutable_list import MutableList
 from sqlalchemy_file.processors import Processor, ThumbnailGenerator
 from sqlalchemy_file.storage import StorageManager
@@ -190,10 +191,10 @@ def extract_files_from_history(cls, data: Union[Tuple[()], List[Any]]) -> List[s
         paths = []
         for item in data:
             if isinstance(item, list):
-                paths.extend([f["path"] for f in item])
+                paths.extend([f["files"] for f in item])
             elif isinstance(item, File):
-                paths.append(item["path"])
-        return paths
+                paths.append(item["files"])
+        return flatmap(paths)
 
     @classmethod
     def _mapper_configured(cls, mapper: Mapper, class_: Any) -> None:  # type: ignore[type-arg]
@@ -242,10 +243,12 @@ def _after_delete(cls, mapper: Mapper, _: Connection, obj: Any) -> None:  # type
             if value is not None:
                 cls.add_old_files_to_session(
                     inspect(obj).session,
-                    [
-                        f["path"]
-                        for f in (value if isinstance(value, list) else [value])
-                    ],
+                    flatmap(
+                        [
+                            f["files"]
+                            for f in (value if isinstance(value, list) else [value])
+                        ]
+                    ),
                 )
 
     @classmethod
@@ -280,7 +283,9 @@ def _before_update(cls, mapper: Mapper, _: Connection, obj: Any) -> None:  # typ
                     )
                 if isinstance(value, MutableList):
                     _removed = getattr(value, "_removed", ())
-                    cls.add_old_files_to_session(session, [f["path"] for f in _removed])
+                    cls.add_old_files_to_session(
+                        session, flatmap([f["files"] for f in _removed])
+                    )
 
     @classmethod
     def _before_insert(cls, mapper: Mapper, _: Connection, obj: Any) -> None:  # type: ignore[type-arg]
diff --git a/tests/test_processor.py b/tests/test_processor.py
index a1b81a3..568ac93 100644
--- a/tests/test_processor.py
+++ b/tests/test_processor.py
@@ -2,6 +2,8 @@
 import tempfile
 
 import pytest
+from libcloud.storage.types import ObjectDoesNotExistError
+from PIL import Image
 from sqlalchemy import Column, Integer, String, select
 from sqlalchemy.orm import Session, declarative_base
 from sqlalchemy_file.storage import StorageManager
@@ -51,8 +53,6 @@ def setup_method(self, method) -> None:
 
     def test_create_image_with_thumbnail(self, fake_image) -> None:
         with Session(engine) as session:
-            from PIL import Image
-
             session.add(Book(title="Pointless Meetings", cover=fake_image))
             session.flush()
             book = session.execute(
@@ -66,6 +66,38 @@ def test_create_image_with_thumbnail(self, fake_image) -> None:
             assert book.cover["thumbnail"]["width"] == thumbnail.width
             assert book.cover["thumbnail"]["height"] == thumbnail.height
 
+    def test_update_image_with_thumbnail(self, fake_image) -> None:
+        with Session(engine) as session:
+            session.add(Book(title="Pointless Meetings", cover=fake_image))
+            session.commit()
+            book = session.execute(
+                select(Book).where(Book.title == "Pointless Meetings")
+            ).scalar_one()
+            old_file_id = book.cover.path
+            old_thumbnail_file_id = book.cover.thumbnail["path"]
+            book.cover = fake_image
+            session.commit()
+            with pytest.raises(ObjectDoesNotExistError):
+                assert StorageManager.get_file(old_file_id)
+            with pytest.raises(ObjectDoesNotExistError):
+                assert StorageManager.get_file(old_thumbnail_file_id)
+
+    def test_delete_image_with_thumbnail(self, fake_image) -> None:
+        with Session(engine) as session:
+            session.add(Book(title="Pointless Meetings", cover=fake_image))
+            session.commit()
+            book = session.execute(
+                select(Book).where(Book.title == "Pointless Meetings")
+            ).scalar_one()
+            old_file_id = book.cover.path
+            old_thumbnail_file_id = book.cover.thumbnail["path"]
+            session.delete(book)
+            session.commit()
+            with pytest.raises(ObjectDoesNotExistError):
+                assert StorageManager.get_file(old_file_id)
+            with pytest.raises(ObjectDoesNotExistError):
+                assert StorageManager.get_file(old_thumbnail_file_id)
+
     def teardown_method(self, method):
         for obj in StorageManager.get().list_objects():
             obj.delete()