diff --git a/ogn/client/client.py b/ogn/client/client.py
index ec7e451..7142d57 100644
--- a/ogn/client/client.py
+++ b/ogn/client/client.py
@@ -7,9 +7,9 @@ from ogn.client import settings
 
 def create_aprs_login(user_name, pass_code, app_name, app_version, aprs_filter=None):
     if not aprs_filter:
-        return "user {} pass {} vers {} {}\n".format(user_name, pass_code, app_name, app_version)
+        return f"user {user_name} pass {pass_code} vers {app_name} {app_version}\n"
     else:
-        return "user {} pass {} vers {} {} filter {}\n".format(user_name, pass_code, app_name, app_version, aprs_filter)
+        return f"user {user_name} pass {pass_code} vers {app_name} {app_version} filter {aprs_filter}\n"
 
 
 class AprsClient:
@@ -46,21 +46,19 @@ class AprsClient:
                 self.sock_file = self.sock.makefile('rb')
 
                 self._kill = False
-                self.logger.info("Connect to OGN ({}/{}:{}) as {} with filter: {}".
-                                 format(self.settings.APRS_SERVER_HOST, self._sock_peer_ip, port, self.aprs_user,
-                                        "'" + self.aprs_filter + "'" if self.aprs_filter else 'none (full-feed)'))
+                self.logger.info(f"Connect to OGN ({self.settings.APRS_SERVER_HOST}/{self._sock_peer_ip}:{port}) as {self.aprs_user} with filter: '{self.aprs_filter}'" if self.aprs_filter else 'none (full-feed)')
                 break
             except (socket.error, ConnectionError) as e:
-                self.logger.error('Connect error: {}'.format(e))
+                self.logger.error(f'Connect error: {e}')
                 if retries > 0:
-                    self.logger.info('Waiting {}s before next connection try ({} attempts left).'.format(wait_period, retries))
+                    self.logger.info(f'Waiting {wait_period}s before next connection try ({retries} attempts left).')
                     sleep(wait_period)
                 else:
                     self._kill = True
                     self.logger.critical('Could not connect to OGN.')
 
     def disconnect(self):
-        self.logger.info('Disconnect from {}'.format(self._sock_peer_ip))
+        self.logger.info(f'Disconnect from {self._sock_peer_ip}')
         try:
             # close everything
             self.sock.shutdown(0)
@@ -77,7 +75,7 @@ class AprsClient:
                 keepalive_time = time()
                 while not self._kill:
                     if time() - keepalive_time > self.settings.APRS_KEEPALIVE_TIME:
-                        self.logger.info('Send keepalive to {}'.format(self._sock_peer_ip))
+                        self.logger.info(f'Send keepalive to {self._sock_peer_ip}')
                         self.sock.send('#keepalive\n'.encode())
                         timed_callback(self)
                         keepalive_time = time()
@@ -95,7 +93,7 @@ class AprsClient:
 
                     callback(packet_str, **kwargs)
             except (socket.error, ConnectionError) as e:
-                self.logger.error('Connect error: {}'.format(e))
+                self.logger.error(f'Connect error: {e}')
             except OSError:
                 self.logger.error('OSError')
             except UnicodeDecodeError:
diff --git a/ogn/parser/aprs_comment/base.py b/ogn/parser/aprs_comment/base.py
index 539d425..5fbbd12 100644
--- a/ogn/parser/aprs_comment/base.py
+++ b/ogn/parser/aprs_comment/base.py
@@ -8,12 +8,12 @@ class BaseParser():
         elif aprs_type.startswith('status'):
             data = self.parse_status(aprs_comment)
         else:
-            raise ValueError("aprs_type {} unknown".format(aprs_type))
+            raise ValueError(f"aprs_type '{aprs_type}' unknown")
         data.update({'beacon_type': self.beacon_type})
         return data
 
     def parse_position(self, aprs_comment):
-        raise NotImplementedError("Position parser for parser '{}' not yet implemented".format(self.beacon_type))
+        raise NotImplementedError(f"Position parser for parser '{self.beacon_type}' not yet implemented")
 
     def parse_status(self, aprs_comment):
-        raise NotImplementedError("Status parser for parser '{}' not yet implemented".format(self.beacon_type))
+        raise NotImplementedError(f"Status parser for parser '{self.beacon_type}' not yet implemented")
diff --git a/ogn/parser/exceptions.py b/ogn/parser/exceptions.py
index 1f8a9ba..9c3dc38 100644
--- a/ogn/parser/exceptions.py
+++ b/ogn/parser/exceptions.py
@@ -12,7 +12,7 @@ class AprsParseError(ParseError):
     def __init__(self, aprs_string):
         self.aprs_string = aprs_string
 
-        self.message = "This is not a valid APRS packet: {}".format(aprs_string)
+        self.message = f"This is not a valid APRS packet: {aprs_string}"
         super(AprsParseError, self).__init__(self.message)
 
 
@@ -21,5 +21,5 @@ class OgnParseError(ParseError):
     def __init__(self, aprs_comment):
         self.aprs_comment = aprs_comment
 
-        self.message = "This is not a valid OGN message: {}".format(aprs_comment)
+        self.message = f"This is not a valid OGN message: {aprs_comment}"
         super(OgnParseError, self).__init__(self.message)
diff --git a/tests/client/test_AprsClient.py b/tests/client/test_AprsClient.py
index 20d0556..b34f8e2 100644
--- a/tests/client/test_AprsClient.py
+++ b/tests/client/test_AprsClient.py
@@ -70,7 +70,7 @@ def test_run(mock_socket):
                                              KeyboardInterrupt()]
 
     try:
-        client.run(callback=lambda msg: print("got: {}".format(msg)), autoreconnect=True)
+        client.run(callback=lambda msg: print(f"got: {msg}"), autoreconnect=True)
     except KeyboardInterrupt:
         pass
     finally:
@@ -95,7 +95,7 @@ def test_run_keepalive(mock_socket, mock_time):
     timed_callback = mock.MagicMock()
 
     try:
-        client.run(callback=lambda msg: print("got: {}".format(msg)), timed_callback=timed_callback)
+        client.run(callback=lambda msg: print(f"got: {msg}"), timed_callback=timed_callback)
     except KeyboardInterrupt:
         pass
     finally:
@@ -137,9 +137,9 @@ def test_50_live_messages():
             return
         try:
             message = parse(raw_message)
-            print("{}: {}".format(message['aprs_type'], raw_message))
+            print(f"{message['aprs_type']}: {raw_message}")
         except NotImplementedError as e:
-            print("{}: {}".format(e, raw_message))
+            print(f"{e}: {raw_message}")
             return
         if remaining_messages > 0:
             remaining_messages -= 1