diff --git a/tools/update-dbus-docs.py b/tools/update-dbus-docs.py
index 99c3db5744..287d378205 100755
--- a/tools/update-dbus-docs.py
+++ b/tools/update-dbus-docs.py
@@ -4,10 +4,10 @@
 
 import argparse
 import collections
-import sys
+import io
 import os
 import subprocess
-import io
+import sys
 
 try:
     from lxml import etree
@@ -19,9 +19,11 @@ try:
 except ImportError as e:
     shlex_join = e
 
+
 class NoCommand(Exception):
     pass
 
+
 BORING_INTERFACES = [
     'org.freedesktop.DBus.Peer',
     'org.freedesktop.DBus.Introspectable',
@@ -34,11 +36,10 @@ RESET = '\x1b[39m'
 
 arguments = None
 
+
 def xml_parser():
-    return etree.XMLParser(no_network=True,
-                           remove_comments=False,
-                           strip_cdata=False,
-                           resolve_entities=False)
+    return etree.XMLParser(no_network=True, remove_comments=False, strip_cdata=False, resolve_entities=False)
+
 
 def print_method(declarations, elem, *, prefix, file, is_signal=False):
     name = elem.get('name')
@@ -61,7 +62,7 @@ def print_method(declarations, elem, *, prefix, file, is_signal=False):
 
         if argname is None:
             if arguments.print_errors:
-                print(f'method {name}: argument {num+1} has no name', file=sys.stderr)
+                print(f'method {name}: argument {num + 1} has no name', file=sys.stderr)
             argname = 'UNNAMED'
 
         argtype = arg.get('type')
@@ -73,19 +74,22 @@ def print_method(declarations, elem, *, prefix, file, is_signal=False):
 
     print(');', file=file)
 
+
 ACCESS_MAP = {
-    'read' : 'readonly',
-    'write' : 'readwrite',
+    'read': 'readonly',
+    'write': 'readwrite',
 }
 
+
 def value_ellipsis(prop_type):
     if prop_type == 's':
         return "'...'"
     if prop_type[0] == 'a':
         inner = value_ellipsis(prop_type[1:])
-        return f"[{inner}{', ...' if inner != '...' else ''}]"
+        return f'[{inner}{", ..." if inner != "..." else ""}]'
     return '...'
 
+
 def print_property(declarations, elem, *, prefix, file):
     prop_name = elem.get('name')
     prop_type = elem.get('type')
@@ -105,11 +109,11 @@ def print_property(declarations, elem, *, prefix, file):
     prop_access = ACCESS_MAP.get(prop_access, prop_access)
     print(f'''{prefix}{prop_access} {prop_type} {prop_name} = {value_ellipsis(prop_type)};''', file=file)
 
+
 def print_interface(iface, *, prefix, file, print_boring, only_interface, declarations):
     name = iface.get('name')
 
-    is_boring = (name in BORING_INTERFACES or
-                 only_interface is not None and name != only_interface)
+    is_boring = name in BORING_INTERFACES or only_interface is not None and name != only_interface
 
     if is_boring and print_boring:
         print(f'''{prefix}interface {name} {{ ... }};''', file=file)
@@ -135,10 +139,11 @@ def print_interface(iface, *, prefix, file, print_boring, only_interface, declar
 
         print(f'''{prefix}}};''', file=file)
 
+
 def check_documented(document, declarations, stats, interface, missing_version):
     missing = []
 
-    sections = document.findall("refsect1")
+    sections = document.findall('refsect1')
     history_section = document.find("refsect1[title = 'History']")
     if history_section is not None:
         sections.remove(history_section)
@@ -171,12 +176,13 @@ def check_documented(document, declarations, stats, interface, missing_version):
                 missing.append((klass, item))
 
             if history_section is None or history_section.find(predicate) is None:
-                missing_version.append(f"{interface}.{item_repr}")
+                missing_version.append(f'{interface}.{item_repr}')
 
     stats['missing'] += len(missing)
 
     return missing
 
+
 def xml_to_text(destination, xml, *, only_interface=None):
     file = io.StringIO()
 
@@ -187,18 +193,23 @@ def xml_to_text(destination, xml, *, only_interface=None):
 
     for print_boring in [False, True]:
         for iface in xml.findall('./interface'):
-            print_interface(iface, prefix='  ', file=file,
-                            print_boring=print_boring,
-                            only_interface=only_interface,
-                            declarations=declarations)
+            print_interface(
+                iface,
+                prefix='  ',
+                file=file,
+                print_boring=print_boring,
+                only_interface=only_interface,
+                declarations=declarations,
+            )
             name = iface.get('name')
-            if not name in BORING_INTERFACES:
+            if name not in BORING_INTERFACES:
                 interfaces.append(name)
 
     print('''};''', file=file)
 
     return file.getvalue(), declarations, interfaces
 
+
 def subst_output(document, programlisting, stats, missing_version):
     executable = programlisting.get('executable', None)
     if executable is None:
@@ -232,17 +243,17 @@ def subst_output(document, programlisting, stats, missing_version):
                 parent.remove(child)
             if child.tag is etree.Comment and 'not documented' in child.text:
                 parent.remove(child)
-            if child.tag == "variablelist" and child.attrib.get("generated", False) == "True":
+            if child.tag == 'variablelist' and child.attrib.get('generated', False) == 'True':
                 parent.remove(child)
 
         # insert pointer for systemd-directives generation
-        the_tail = programlisting.tail #tail is erased by addnext, so save it here.
-        prev_element = etree.Comment("Autogenerated cross-references for systemd.directives, do not edit")
+        the_tail = programlisting.tail  # tail is erased by addnext, so save it here.
+        prev_element = etree.Comment('Autogenerated cross-references for systemd.directives, do not edit')
         programlisting.addnext(prev_element)
         programlisting.tail = the_tail
 
         for interface in interfaces:
-            variablelist = etree.Element("variablelist")
+            variablelist = etree.Element('variablelist')
             variablelist.attrib['class'] = 'dbus-interface'
             variablelist.attrib['generated'] = 'True'
             variablelist.attrib['extra-ref'] = interface
@@ -251,10 +262,10 @@ def subst_output(document, programlisting, stats, missing_version):
             prev_element.tail = the_tail
             prev_element = variablelist
 
-        for decl_type,decl_list in declarations.items():
+        for decl_type, decl_list in declarations.items():
             for declaration in decl_list:
-                variablelist = etree.Element("variablelist")
-                variablelist.attrib['class'] = 'dbus-'+decl_type
+                variablelist = etree.Element('variablelist')
+                variablelist.attrib['class'] = 'dbus-' + decl_type
                 variablelist.attrib['generated'] = 'True'
                 if decl_type in ('method', 'signal'):
                     variablelist.attrib['extra-ref'] = declaration + '()'
@@ -265,7 +276,7 @@ def subst_output(document, programlisting, stats, missing_version):
                 prev_element.tail = the_tail
                 prev_element = variablelist
 
-        last_element = etree.Comment("End of Autogenerated section")
+        last_element = etree.Comment('End of Autogenerated section')
         prev_element.addnext(last_element)
         prev_element.tail = the_tail
         last_element.tail = the_tail
@@ -276,6 +287,7 @@ def subst_output(document, programlisting, stats, missing_version):
             comment.tail = programlisting.tail
             parent.insert(parent.index(programlisting) + 1, comment)
 
+
 def process(page, missing_version):
     src = open(page).read()
     xml = etree.fromstring(src, parser=xml_parser())
@@ -293,26 +305,35 @@ def process(page, missing_version):
     out_text = etree.tostring(xml, encoding='unicode')
     # massage format to avoid some lxml whitespace handling idiosyncrasies
     # https://bugs.launchpad.net/lxml/+bug/526799
-    out_text = (src[:src.find('<refentryinfo')] +
-                out_text[out_text.find('<refentryinfo'):] +
-                '\n')
+    out_text = src[: src.find('<refentryinfo')] + out_text[out_text.find('<refentryinfo') :] + '\n'
 
     if not arguments.test:
         with open(page, 'w') as out:
             out.write(out_text)
 
-    return { "stats" : stats, "modified" : out_text != src }
+    return {'stats': stats, 'modified': out_text != src}
+
 
 def parse_args():
     p = argparse.ArgumentParser()
-    p.add_argument('--test', action='store_true',
-                   help='only verify that everything is up2date')
-    p.add_argument('--build-dir', default='build')
-    p.add_argument('pages', nargs='+')
+    p.add_argument(
+        '--test',
+        action='store_true',
+        help='only verify that everything is up2date',
+    )
+    p.add_argument(
+        '--build-dir',
+        default='build',
+    )
+    p.add_argument(
+        'pages',
+        nargs='+',
+    )
     opts = p.parse_args()
     opts.print_errors = not opts.test
     return opts
 
+
 def main():
     # pylint: disable=global-statement
     global arguments
@@ -327,13 +348,13 @@ def main():
         sys.exit(f"{arguments.build_dir} doesn't exist.")
 
     missing_version = []
-    stats = {page.split('/')[-1] : process(page, missing_version) for page in arguments.pages}
+    stats = {page.split('/')[-1]: process(page, missing_version) for page in arguments.pages}
 
     ignore_list = open(os.path.join(os.path.dirname(__file__), 'dbus_ignorelist')).read().split()
     missing_version = [x for x in missing_version if x not in ignore_list]
 
     for missing in missing_version:
-        print(f"{RED}Missing version information for {missing}{RESET}")
+        print(f'{RED}Missing version information for {missing}{RESET}')
 
     if missing_version:
         sys.exit(1)
@@ -341,7 +362,7 @@ def main():
     # Let's print all statistics at the end
     mlen = max(len(page) for page in stats)
     total = sum((item['stats'] for item in stats.values()), start=collections.Counter())
-    total = 'total', { "stats" : total, "modified" : False }
+    total = 'total', {'stats': total, 'modified': False}
     modified = []
     classification = 'OUTDATED' if arguments.test else 'MODIFIED'
     for page, info in sorted(stats.items()) + [total]:
@@ -351,12 +372,15 @@ def main():
         c = classification if info['modified'] else ''
         if c:
             modified.append(page)
-        color = RED if m > t/2 else (YELLOW if m else GREEN)
+        color = RED if m > t / 2 else (YELLOW if m else GREEN)
         print(f'{color}{p:{mlen + 1}} {t - m}/{t} {c}{RESET}')
 
     if arguments.test and modified:
-        sys.exit(f'Outdated pages: {", ".join(modified)}\n'
-                 f'Hint: ninja -C {arguments.build_dir} update-dbus-docs')
+        sys.exit(
+            f'Outdated pages: {", ".join(modified)}\n'
+            f'Hint: ninja -C {arguments.build_dir} update-dbus-docs'
+        )  # fmt: skip
+
 
 if __name__ == '__main__':
     main()