diff --git a/nvchecker/core.py b/nvchecker/core.py
index e753eeb..e74a88a 100644
--- a/nvchecker/core.py
+++ b/nvchecker/core.py
@@ -57,7 +57,7 @@ def add_common_arguments(parser: argparse.ArgumentParser) -> None:
   parser.add_argument('-c', '--file',
                       metavar='FILE', type=str,
                       default=default_config,
-                      help='software version configuration file [default: %s]' % default_config)
+                      help=f'software version configuration file [default: {default_config}]')
 
 def process_common_arguments(args: argparse.Namespace) -> bool:
   '''return True if should stop'''
@@ -94,7 +94,7 @@ def process_common_arguments(args: argparse.Namespace) -> bool:
 
   if args.version:
     progname = os.path.basename(sys.argv[0])
-    print('%s v%s' % (progname, __version__))
+    print(f'{progname} v{__version__}')
     return True
   return False
 
diff --git a/nvchecker/ctxvars.py b/nvchecker/ctxvars.py
index 2f5b49a..e9daf71 100644
--- a/nvchecker/ctxvars.py
+++ b/nvchecker/ctxvars.py
@@ -8,7 +8,7 @@ from typing import Optional
 
 from . import __version__
 
-DEFAULT_USER_AGENT = 'lilydjwg/nvchecker %s' % __version__
+DEFAULT_USER_AGENT = f'lilydjwg/nvchecker {__version__}'
 
 tries = ContextVar('tries', default=1)
 proxy: ContextVar[Optional[str]] = ContextVar('proxy', default=None)
diff --git a/nvchecker/slogconf.py b/nvchecker/slogconf.py
index c0db526..fefb86e 100644
--- a/nvchecker/slogconf.py
+++ b/nvchecker/slogconf.py
@@ -27,7 +27,7 @@ def _console_msg(event):
     msg = evt
 
   if 'name' in event:
-    msg = '%s: %s' % (event['name'], msg)
+    msg = f"{event['name']}: {msg}"
     del event['name']
 
   event['msg'] = msg
diff --git a/nvchecker_source/gitea.py b/nvchecker_source/gitea.py
index 17cb558..0ff3a93 100644
--- a/nvchecker_source/gitea.py
+++ b/nvchecker_source/gitea.py
@@ -36,7 +36,7 @@ async def get_version(
   # Set private token if token exists.
   headers = {}
   if token:
-    headers["Authorization"] = 'token %s' % token
+    headers["Authorization"] = f'token {token}'
 
   data = await cache.get_json(url, headers = headers)
   if use_max_tag:
diff --git a/nvchecker_source/github.py b/nvchecker_source/github.py
index 36414b7..0920d54 100644
--- a/nvchecker_source/github.py
+++ b/nvchecker_source/github.py
@@ -46,7 +46,7 @@ async def get_latest_tag(key: Tuple[str, str, str]) -> str:
   repo, query, token = key
   owner, reponame = repo.split('/')
   headers = {
-    'Authorization': 'bearer %s' % token,
+    'Authorization': f'bearer {token}',
     'Content-Type': 'application/json',
   }
   q = QUERY_LATEST_TAG.format(
@@ -109,7 +109,7 @@ async def get_version_real(
     'Accept': 'application/vnd.github.quicksilver-preview+json',
   }
   if token:
-    headers['Authorization'] = 'token %s' % token
+    headers['Authorization'] = f'token {token}'
 
   data = await cache.get_json(url, headers = headers)
 
@@ -140,9 +140,8 @@ def check_ratelimit(exc, name):
   n = int(res.headers.get('X-RateLimit-Remaining', -1))
   if n == 0:
     reset = int(res.headers.get('X-RateLimit-Reset'))
-    logger.error('rate limited, resetting at %s. '
-                 'Or get an API token to increase the allowance if not yet'
-                 % time.ctime(reset),
+    logger.error(f'rate limited, resetting at {time.ctime(reset)}. '
+                  'Or get an API token to increase the allowance if not yet',
                  name = name,
                  reset = reset)
   else:
diff --git a/scripts/maintained_in_aur b/scripts/maintained_in_aur
index c351996..37dff6b 100755
--- a/scripts/maintained_in_aur
+++ b/scripts/maintained_in_aur
@@ -9,10 +9,10 @@ import json
 import urllib.request
 
 def main(user):
-  url = 'https://aur.archlinux.org/rpc.php?type=msearch&arg=' + user
+  url = f'https://aur.archlinux.org/rpc.php?type=msearch&arg={user}'
   res = urllib.request.urlopen(url)
   if res.status != 200:
-    sys.exit('Error: %d %s' % (res.status, res.reason))
+    sys.exit(f'Error: {res.status} {res.reason}')
   d = res.read().decode('utf-8')
   d = json.loads(d)
   print('\n'.join(sorted(pkg['Name'] for pkg in d['results'])))