diff --git a/vermouth/deferred_file.py b/vermouth/deferred_file.py
deleted file mode 100644
index 0275729a..00000000
--- a/vermouth/deferred_file.py
+++ /dev/null
@@ -1,192 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2018 University of Groningen
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#    http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-"""
-Provides a class that can be used to write to temporary files, which should be
-moved to a specified location if no errors occured.
-"""
-
-import logging
-import os
-import sys
-import tempfile
-
-from .log_helpers import StyleAdapter
-
-LOGGER = StyleAdapter(logging.getLogger(__name__))
-
-
-# TODO: replace with pathlib.replace, and add pathlib2 to requirements for py2.7.
-# from https://stupidpythonideas.blogspot.nl/2014/07/getting-atomic-writes-right.html
-try:
-    replace = os.replace  # pylint: disable=invalid-name
-except AttributeError:
-    if sys.platform == 'win32':
-        import win32api  # pylint: disable=import-error
-        import win32con  # pylint: disable=import-error
-
-        def replace(src, dst):
-            """Atomic move `src` to `dst`"""
-            win32api.MoveFileEx(src, dst, win32con.MOVEFILE_REPLACE_EXISTING)
-    else:
-        replace = os.rename  # pylint: disable=invalid-name
-
-
-def find_next_filename(basename, suffix='bak'):
-    """
-    Generates the next available filename for `basename`.
-    If `basename` does not exist, returns `basename`.
-    If `basename` exists, returns `basename.suffix`.
-    If `basename.suffix` exists, returns `basename.suffix.2`.
-    If `basename.suffix.n` exists, returns `basename.suffix.n+1`
-
-    Parameters
-    ----------
-    basename: str
-    suffix: str
-
-    Returns
-    -------
-    str
-        The first available filename.
-    """
-    def count_to_ext(count):
-        """
-        Transforms `count` to a filename suffix such as '.bak.3'.
-        """
-        if count < 0:
-            return ''
-        elif count == 0:
-            return os.path.extsep + suffix
-        else:
-            return '{extsep}{suffix}{extsep}{n}'.format(extsep=os.path.extsep,
-                                                        suffix=suffix, n=count)
-    count = -1
-    filename = basename
-    while os.path.exists(filename):
-        count += 1
-        filename = basename + count_to_ext(count)
-    return filename
-
-
-def replace_with_backup(file_in, file_out, suffix='bak'):
-    """
-    Moves `file_in` to `file_out`, backing up `file_out` if it already exists.
-    Uses :func:`find_next_filename` to find a new filename for `file_out` if
-    needed.
-
-    Parameters
-    ----------
-    file_in: str
-        The file to move.
-    file_out: str
-        The filename to move `file_in` to.
-    suffix: str
-        The suffix to use if `file_out` has to be backed up.
-
-    See Also
-    --------
-    :func:`find_next_filename`
-    """
-    if os.path.exists(file_out):
-        file_out_bak = find_next_filename(file_out, suffix=suffix)
-        LOGGER.info('Backing up {} to {}', file_out, file_out_bak)
-        replace(file_out, file_out_bak)
-    return replace(file_in, file_out)
-
-
-class DeferredFile:
-    """
-    Creates a temporary file when opened, to which data can be written. When
-    the changes have been approved (e.g. no warnings were issued) and the file
-    closed, move the temporary file to `filename`.
-
-    Provides a context manager.
-
-    Attributes
-    ----------
-    filename: str
-        The filename to move the temporary file to iff `approved` is ``True``.
-    approved: bool
-        Whether the changes have been approved.
-    """
-    def __init__(self, filename, **kwargs):
-        """
-        Parameters
-        ----------
-        filename: str
-            The filename to move the file to.
-        """
-        self.filename = filename
-        self.approved = False
-        self._tempfile = None
-
-    def open(self):
-        """
-        Open a temporary file for writing.
-        """
-        self._tempfile = tempfile.NamedTemporaryFile(mode='w', delete=False)
-
-    def approve(self):
-        """
-        Approve the changes made.
-        """
-        self.approved = True
-
-    def close(self):
-        """
-        Close the temporary file, and if the changes have been approved, move
-        it to the correct location. Otherwise, remove it.
-        """
-        self._tempfile.close()
-        if self.approved:
-            replace_with_backup(self._tempfile.name, self.filename)
-        else:
-            os.remove(self._tempfile.name)
-
-    # For some reason tempfile.NamedTemporaryFile is a function, not a class.
-    # And to top it off, the object it returns has a magic getattr method...
-    def write(self, *args, **kwargs):
-        """
-        Write to the temporary file.
-
-        See Also
-        --------
-        :func:`tempfile.NamedTemporaryFile`
-        """
-        self._tempfile.write(*args, **kwargs)
-
-    def __enter__(self):
-        self.open()
-        return self
-
-    def __exit__(self, exc_type, exc_value, traceback):
-        if exc_type is not None:  # An exception happened
-            self.approved = False
-        self.close()
-        return False  # re-raise any exceptions
-
-
-# if __name__ == '__main__':
-#     dfile = DeferredFile('flup1.txt')
-#     dfile.open()
-#     dfile.write('boe')
-#     dfile.close()
-#
-#     with DeferredFile('flup.txt') as df:
-#         df.write('Hello!')
-#
-#     with DeferredFile('flup2.txt') as df:
-#         df.write('World!')
-#         df.approve()