diff --git a/fileformats/core/fileset.py b/fileformats/core/fileset.py
index e45885c..c4e6d8d 100644
--- a/fileformats/core/fileset.py
+++ b/fileformats/core/fileset.py
@@ -949,30 +949,6 @@ def hash_files(
             file_hashes[str(path)] = crypto_obj.hexdigest()
         return file_hashes
 
-    def __bytes_repr__(
-        self, cache: ty.Dict[ty.Any, str]  # pylint: disable=unused-argument
-    ) -> ty.Iterable[bytes]:
-        """Provided for compatibility with Pydra's hashing function, return the contents
-        of all the files in the file-set in chunks
-
-        Parameters
-        ----------
-        cache : dict[Any, str]
-            an object passed around by Pydra's hashing function to store cached versions
-            of previously hashed objects, to allow recursive structures
-
-        Yields
-        ------
-        bytes
-            a chunk of bytes of length FILE_CHUNK_LEN_DEFAULT from the contents of all
-            files in the file-set.
-        """
-        cls = type(self)
-        yield f"{cls.__module__}.{cls.__name__}:".encode()
-        for key, chunk_iter in self.byte_chunks():
-            yield (",'" + key + "'=").encode()
-            yield from chunk_iter
-
     @classmethod
     def referenced_types(cls) -> ty.Set[ty.Type[Classifier]]:
         """Returns a flattened list of nested types referenced within the fileset type
diff --git a/fileformats/core/tests/test_utils.py b/fileformats/core/tests/test_utils.py
index feb5f1c..fcf2c74 100644
--- a/fileformats/core/tests/test_utils.py
+++ b/fileformats/core/tests/test_utils.py
@@ -5,8 +5,14 @@
 import time
 import typing as ty
 import pytest
-from fileformats.core import FileSet, validated_property
-from fileformats.generic import File, BinaryFile, Directory, FsObject
+from fileformats.generic import File, BinaryFile, Directory, FsObject, SetOf
+from fileformats.core import (
+    FileSet,
+    MockMixin,
+    validated_property,
+    mtime_cached_property,
+)
+from fileformats.text import TextFile
 from fileformats.core.mixin import WithSeparateHeader
 from fileformats.core.exceptions import UnsatisfiableCopyModeError
 from conftest import write_test_file
@@ -54,6 +60,11 @@ def fsobject(luigi_file, bowser_dir, request):
         assert False
 
 
+@pytest.fixture
+def mock_fileset():
+    return SetOf[TextFile].mock("/path/to/a/mock", "/path/to/another/mock")
+
+
 @pytest.fixture
 def dest_dir(work_dir):
     dest_dir = work_dir / "new-dir"
@@ -523,3 +534,51 @@ def test_hash_files(fsobject: FsObject, work_dir: Path, dest_dir: Path):
     )
     cpy = fsobject.copy(dest_dir)
     assert cpy.hash_files() == fsobject.hash_files()
+
+
+class MtimeTestFile(File):
+
+    flag: int
+
+    @mtime_cached_property
+    def cached_prop(self):
+        return self.flag
+
+
+def test_mtime_cached_property(tmp_path: Path):
+    fspath = tmp_path / "file_1.txt"
+    fspath.write_text("hello")
+
+    file = MtimeTestFile(fspath)
+
+    file.flag = 0
+    assert file.cached_prop == 0
+    # Need a long delay to ensure the mtime changes on Ubuntu and particularly on Windows
+    # On MacOS, the mtime resolution is much higher so not usually an issue. Use
+    # explicitly cache clearing if needed
+    time.sleep(2)
+    file.flag = 1
+    assert file.cached_prop == 0
+    time.sleep(2)
+    fspath.write_text("world")
+    assert file.cached_prop == 1
+
+
+def test_mtime_cached_property_force_clear(tmp_path: Path):
+    fspath = tmp_path / "file_1.txt"
+    fspath.write_text("hello")
+
+    file = MtimeTestFile(fspath)
+
+    file.flag = 0
+    assert file.cached_prop == 0
+    file.flag = 1
+    MtimeTestFile.cached_prop.clear(file)
+    assert file.cached_prop == 1
+
+
+def test_hash_mock_files(mock_fileset: MockMixin, work_dir: Path, dest_dir: Path):
+    file_hashes = mock_fileset.hash_files(relative_to="")
+    assert sorted(Path(p) for p in file_hashes) == sorted(
+        p for p in mock_fileset.fspaths
+    )