diff --git a/vcsserver/git_lfs/lib.py b/vcsserver/git_lfs/lib.py
--- a/vcsserver/git_lfs/lib.py
+++ b/vcsserver/git_lfs/lib.py
@@ -130,7 +130,7 @@ class LFSOidStore:
             f.write('...')
         """
 
-        class StoreEngine(object):
+        class StoreEngine:
             def __init__(self, mode, store_path, oid_path, tmp_oid_path):
                 self.mode = mode
                 self.store_path = store_path
diff --git a/vcsserver/lib/_vendor/statsd/base.py b/vcsserver/lib/_vendor/statsd/base.py
--- a/vcsserver/lib/_vendor/statsd/base.py
+++ b/vcsserver/lib/_vendor/statsd/base.py
@@ -71,7 +71,7 @@ class StatsClientBase:
 
     def incr(self, stat, count=1, rate=1, tags=None):
         """Increment a stat by `count`."""
-        self._send_stat(stat, '%s|c' % count, rate, tags)
+        self._send_stat(stat, f'{count}|c', rate, tags)
 
     def decr(self, stat, count=1, rate=1, tags=None):
         """Decrement a stat by `count`."""
@@ -85,18 +85,18 @@ class StatsClientBase:
                     return
             with self.pipeline() as pipe:
                 pipe._send_stat(stat, '0|g', 1)
-                pipe._send_stat(stat, '%s|g' % value, 1)
+                pipe._send_stat(stat, f'{value}|g', 1)
         else:
             prefix = '+' if delta and value >= 0 else ''
-            self._send_stat(stat, '%s%s|g' % (prefix, value), rate, tags)
+            self._send_stat(stat, f'{prefix}{value}|g', rate, tags)
 
     def set(self, stat, value, rate=1):
         """Set a set value."""
-        self._send_stat(stat, '%s|s' % value, rate)
+        self._send_stat(stat, f'{value}|s', rate)
 
     def histogram(self, stat, value, rate=1, tags=None):
         """Set a histogram"""
-        self._send_stat(stat, '%s|h' % value, rate, tags)
+        self._send_stat(stat, f'{value}|h', rate, tags)
 
     def _send_stat(self, stat, value, rate, tags=None):
         self._after(self._prepare(stat, value, rate, tags))
@@ -108,10 +108,10 @@ class StatsClientBase:
         if rate < 1:
             if random.random() > rate:
                 return
-            value = '%s|@%s' % (value, rate)
+            value = f'{value}|@{rate}'
 
         if self._prefix:
-            stat = '%s.%s' % (self._prefix, stat)
+            stat = f'{self._prefix}.{stat}'
 
         res = '%s:%s%s' % (
             stat,
diff --git a/vcsserver/pygrack.py b/vcsserver/pygrack.py
--- a/vcsserver/pygrack.py
+++ b/vcsserver/pygrack.py
@@ -123,7 +123,7 @@ class GitRepository:
         # blows up if you sprinkle "flush" (0000) as "0001\n".
         # It reads binary, per number of bytes specified.
         # if you do add '\n' as part of data, count it.
-        server_advert = '# service=%s\n' % git_command
+        server_advert = f'# service={git_command}\n'
         packet_len = hex(len(server_advert) + 4)[2:].rjust(4, '0').lower()
         try:
             gitenv = dict(os.environ)
diff --git a/vcsserver/tests/test_install_hooks.py b/vcsserver/tests/test_install_hooks.py
--- a/vcsserver/tests/test_install_hooks.py
+++ b/vcsserver/tests/test_install_hooks.py
@@ -59,7 +59,7 @@ class BaseInstallHooks:
     HOOK_FILES = ()
 
     def _check_hook_file_mode(self, file_path):
-        assert os.path.exists(file_path), 'path %s missing' % file_path
+        assert os.path.exists(file_path), f'path {file_path} missing'
         stat_info = os.stat(file_path)
 
         file_mode = stat.S_IMODE(stat_info.st_mode)