diff --git a/can/interfaces/ics_neovi/neovi_bus.py b/can/interfaces/ics_neovi/neovi_bus.py
index bd4fc5445..4972ed479 100644
--- a/can/interfaces/ics_neovi/neovi_bus.py
+++ b/can/interfaces/ics_neovi/neovi_bus.py
@@ -171,8 +171,8 @@ def __init__(self, channel, can_filters=None, **kwargs):
 
         super().__init__(channel=channel, can_filters=can_filters, **kwargs)
 
-        logger.info("CAN Filters: {}".format(can_filters))
-        logger.info("Got configuration of: {}".format(kwargs))
+        logger.info(f"CAN Filters: {can_filters}")
+        logger.info(f"Got configuration of: {kwargs}")
 
         if "override_library_name" in kwargs:
             ics.override_library_name(kwargs.get("override_library_name"))
@@ -215,12 +215,12 @@ def __init__(self, channel, can_filters=None, **kwargs):
         self._use_system_timestamp = bool(kwargs.get("use_system_timestamp", False))
         self._receive_own_messages = kwargs.get("receive_own_messages", True)
 
-        self.channel_info = "%s %s CH:%s" % (
+        self.channel_info = "{} {} CH:{}".format(
             self.dev.Name,
             self.get_serial_number(self.dev),
             self.channels,
         )
-        logger.info("Using device: {}".format(self.channel_info))
+        logger.info(f"Using device: {self.channel_info}")
 
         self.rx_buffer = deque()
         self.message_receipts = defaultdict(Event)
@@ -230,7 +230,7 @@ def channel_to_netid(channel_name_or_id):
         try:
             channel = int(channel_name_or_id)
         except ValueError:
-            netid = "NETID_{}".format(channel_name_or_id.upper())
+            netid = f"NETID_{channel_name_or_id.upper()}"
             if hasattr(ics, netid):
                 channel = getattr(ics, netid)
             else:
@@ -298,9 +298,9 @@ def _find_device(self, type_filter=None, serial=None):
             msg = ["No device"]
 
             if type_filter is not None:
-                msg.append("with type {}".format(type_filter))
+                msg.append(f"with type {type_filter}")
             if serial is not None:
-                msg.append("with serial {}".format(serial))
+                msg.append(f"with serial {serial}")
             msg.append("found.")
             raise CanInitializationError(" ".join(msg))
 
diff --git a/can/interfaces/ixxat/canlib_vcinpl.py b/can/interfaces/ixxat/canlib_vcinpl.py
index fa88e5f90..d74da2539 100644
--- a/can/interfaces/ixxat/canlib_vcinpl.py
+++ b/can/interfaces/ixxat/canlib_vcinpl.py
@@ -119,7 +119,7 @@ def __check_status(result, function, args):
         result = ctypes.c_ulong(result).value
 
     if result == constants.VCI_E_TIMEOUT:
-        raise VCITimeout("Function {} timed out".format(function._name))
+        raise VCITimeout(f"Function {function._name} timed out")
     elif result == constants.VCI_E_RXQUEUE_EMPTY:
         raise VCIRxQueueEmptyError()
     elif result == constants.VCI_E_NO_MORE_ITEMS:
@@ -469,7 +469,7 @@ def __init__(
         channel = int(channel)
 
         if bitrate not in self.CHANNEL_BITRATES[0]:
-            raise ValueError("Invalid bitrate {}".format(bitrate))
+            raise ValueError(f"Invalid bitrate {bitrate}")
 
         if rx_fifo_size <= 0:
             raise ValueError("rx_fifo_size must be > 0")
@@ -887,7 +887,7 @@ def _format_can_status(status_flags: int):
             status_flags &= ~flag
 
     if status_flags:
-        states.append("unknown state 0x{:02x}".format(status_flags))
+        states.append(f"unknown state 0x{status_flags:02x}")
 
     if states:
         return "CAN status message: {}".format(", ".join(states))
diff --git a/can/interfaces/ixxat/canlib_vcinpl2.py b/can/interfaces/ixxat/canlib_vcinpl2.py
index 108ad2c02..2e3125e9b 100644
--- a/can/interfaces/ixxat/canlib_vcinpl2.py
+++ b/can/interfaces/ixxat/canlib_vcinpl2.py
@@ -117,7 +117,7 @@ def __check_status(result, function, args):
             :class:VCIError
     """
     if result == constants.VCI_E_TIMEOUT:
-        raise VCITimeout("Function {} timed out".format(function._name))
+        raise VCITimeout(f"Function {function._name} timed out")
     elif result == constants.VCI_E_RXQUEUE_EMPTY:
         raise VCIRxQueueEmptyError()
     elif result == constants.VCI_E_NO_MORE_ITEMS:
@@ -1011,7 +1011,7 @@ def _format_can_status(status_flags: int):
             status_flags &= ~flag
 
     if status_flags:
-        states.append("unknown state 0x{:02x}".format(status_flags))
+        states.append(f"unknown state 0x{status_flags:02x}")
 
     if states:
         return "CAN status message: {}".format(", ".join(states))
diff --git a/can/interfaces/ixxat/structures.py b/can/interfaces/ixxat/structures.py
index b784437e0..419a52973 100644
--- a/can/interfaces/ixxat/structures.py
+++ b/can/interfaces/ixxat/structures.py
@@ -162,7 +162,7 @@ class CANMSG(ctypes.Structure):
     ]
 
     def __str__(self) -> str:
-        return """ID: 0x{0:04x}{1} DLC: {2:02d} DATA: {3}""".format(
+        return """ID: 0x{:04x}{} DLC: {:02d} DATA: {}""".format(
             self.dwMsgId,
             "[RTR]" if self.uMsgInfo.Bits.rtr else "",
             self.uMsgInfo.Bits.dlc,
diff --git a/can/interfaces/kvaser/canlib.py b/can/interfaces/kvaser/canlib.py
index f60a43bc5..a8bb7bac7 100644
--- a/can/interfaces/kvaser/canlib.py
+++ b/can/interfaces/kvaser/canlib.py
@@ -410,8 +410,8 @@ def __init__(self, channel, can_filters=None, **kwargs):
 
         """
 
-        log.info("CAN Filters: {}".format(can_filters))
-        log.info("Got configuration of: {}".format(kwargs))
+        log.info(f"CAN Filters: {can_filters}")
+        log.info(f"Got configuration of: {kwargs}")
         bitrate = kwargs.get("bitrate", 500000)
         tseg1 = kwargs.get("tseg1", 0)
         tseg2 = kwargs.get("tseg2", 0)
diff --git a/can/interfaces/nixnet.py b/can/interfaces/nixnet.py
index f1def62ad..1eba09b31 100644
--- a/can/interfaces/nixnet.py
+++ b/can/interfaces/nixnet.py
@@ -124,7 +124,7 @@ def __init__(
             ) from None
 
         self._is_filtered = False
-        super(NiXNETcanBus, self).__init__(
+        super().__init__(
             channel=channel,
             can_filters=can_filters,
             bitrate=bitrate,
diff --git a/can/interfaces/pcan/basic.py b/can/interfaces/pcan/basic.py
index 38ded44f6..743fb55ee 100644
--- a/can/interfaces/pcan/basic.py
+++ b/can/interfaces/pcan/basic.py
@@ -663,7 +663,7 @@ def __init__(self):
             try:
                 aKey = winreg.OpenKey(aReg, r"SOFTWARE\PEAK-System\PEAK-Drivers")
                 winreg.CloseKey(aKey)
-            except WindowsError:
+            except OSError:
                 logger.error("Exception: The PEAK-driver couldn't be found!")
             finally:
                 winreg.CloseKey(aReg)
diff --git a/can/interfaces/pcan/pcan.py b/can/interfaces/pcan/pcan.py
index c60b9e6c9..cd0349c99 100644
--- a/can/interfaces/pcan/pcan.py
+++ b/can/interfaces/pcan/pcan.py
@@ -218,7 +218,7 @@ def __init__(
             channel = self._find_channel_by_dev_id(device_id)
 
             if channel is None:
-                err_msg = "Cannot find a channel with ID {:08x}".format(device_id)
+                err_msg = f"Cannot find a channel with ID {device_id:08x}"
                 raise ValueError(err_msg)
 
         self.channel_info = str(channel)
@@ -249,7 +249,7 @@ def __init__(
                 f_clock = "{}={}".format("f_clock", kwargs.get("f_clock", None))
 
             fd_parameters_values = [f_clock] + [
-                "{}={}".format(key, kwargs.get(key, None))
+                f"{key}={kwargs.get(key, None)}"
                 for key in PCAN_FD_PARAMETER_LIST
                 if kwargs.get(key, None) is not None
             ]
@@ -350,7 +350,7 @@ def bits(n):
             for b in bits(error):
                 stsReturn = self.m_objPCANBasic.GetErrorText(b, 0x9)
                 if stsReturn[0] != PCAN_ERROR_OK:
-                    text = "An error occurred. Error-code's text ({0:X}h) couldn't be retrieved".format(
+                    text = "An error occurred. Error-code's text ({:X}h) couldn't be retrieved".format(
                         error
                     )
                 else:
diff --git a/can/interfaces/robotell.py b/can/interfaces/robotell.py
index 0d3ad1b77..4d82c1922 100644
--- a/can/interfaces/robotell.py
+++ b/can/interfaces/robotell.py
@@ -396,7 +396,7 @@ def get_serial_number(self, timeout: Optional[int]) -> Optional[str]:
 
         serial = ""
         for idx in range(0, 8, 2):
-            serial += "{:02X}{:02X}-".format(sn1[idx], sn1[idx + 1])
+            serial += f"{sn1[idx]:02X}{sn1[idx + 1]:02X}-"
         for idx in range(0, 4, 2):
-            serial += "{:02X}{:02X}-".format(sn2[idx], sn2[idx + 1])
+            serial += f"{sn2[idx]:02X}{sn2[idx + 1]:02X}-"
         return serial[:-1]
diff --git a/can/interfaces/socketcan/socketcan.py b/can/interfaces/socketcan/socketcan.py
index 549998dc8..66e2923c4 100644
--- a/can/interfaces/socketcan/socketcan.py
+++ b/can/interfaces/socketcan/socketcan.py
@@ -68,7 +68,7 @@ def bcm_header_factory(
         # requirements of this field, then we must add padding bytes until we
         # are aligned
         while curr_stride % field_alignment != 0:
-            results.append(("pad_{}".format(pad_index), ctypes.c_uint8))
+            results.append((f"pad_{pad_index}", ctypes.c_uint8))
             pad_index += 1
             curr_stride += 1
 
@@ -84,7 +84,7 @@ def bcm_header_factory(
     # Add trailing padding to align to a multiple of the largest scalar member
     # in the structure
     while curr_stride % alignment != 0:
-        results.append(("pad_{}".format(pad_index), ctypes.c_uint8))
+        results.append((f"pad_{pad_index}", ctypes.c_uint8))
         pad_index += 1
         curr_stride += 1
 
diff --git a/can/interfaces/socketcan/utils.py b/can/interfaces/socketcan/utils.py
index 55e7eb392..ecc870ca4 100644
--- a/can/interfaces/socketcan/utils.py
+++ b/can/interfaces/socketcan/utils.py
@@ -21,7 +21,7 @@ def pack_filters(can_filters: Optional[typechecking.CanFilters] = None) -> bytes
         # Pass all messages
         can_filters = [{"can_id": 0, "can_mask": 0}]
 
-    can_filter_fmt = "={}I".format(2 * len(can_filters))
+    can_filter_fmt = f"={2 * len(can_filters)}I"
     filter_data = []
     for can_filter in can_filters:
         can_id = can_filter["can_id"]
@@ -50,7 +50,7 @@ def find_available_interfaces() -> Iterable[str]:
     try:
         # adding "type vcan" would exclude physical can devices
         command = ["ip", "-o", "link", "list", "up"]
-        output = subprocess.check_output(command, universal_newlines=True)
+        output = subprocess.check_output(command, text=True)
 
     except Exception as e:  # subprocess.CalledProcessError is too specific
         log.error("failed to fetch opened can devices: %s", e)
diff --git a/can/interfaces/socketcand/socketcand.py b/can/interfaces/socketcand/socketcand.py
index 327df9e73..28f0c700f 100644
--- a/can/interfaces/socketcand/socketcand.py
+++ b/can/interfaces/socketcand/socketcand.py
@@ -43,7 +43,7 @@ def convert_can_message_to_ascii_message(can_message: can.Message) -> str:
     # Note: seems like we cannot add CANFD_BRS (bitrate_switch) and CANFD_ESI (error_state_indicator) flags
     data = can_message.data
     length = can_message.dlc
-    bytes_string = " ".join("{:x}".format(x) for x in data[0:length])
+    bytes_string = " ".join(f"{x:x}" for x in data[0:length])
     return f"< send {can_id:X} {length:X} {bytes_string} >"
 
 
diff --git a/can/interfaces/systec/ucanbus.py b/can/interfaces/systec/ucanbus.py
index fee110b08..7d8b6133a 100644
--- a/can/interfaces/systec/ucanbus.py
+++ b/can/interfaces/systec/ucanbus.py
@@ -134,7 +134,7 @@ def __init__(self, channel, can_filters=None, **kwargs):
             self._ucan.init_hardware(device_number=device_number)
             self._ucan.init_can(self.channel, **self._params)
             hw_info_ex, _, _ = self._ucan.get_hardware_info()
-            self.channel_info = "%s, S/N %s, CH %s, BTR %s" % (
+            self.channel_info = "{}, S/N {}, CH {}, BTR {}".format(
                 self._ucan.get_product_code_message(hw_info_ex.product_code),
                 hw_info_ex.serial,
                 self.channel,
diff --git a/can/interfaces/vector/canlib.py b/can/interfaces/vector/canlib.py
index 8f699f3f7..aed916cdb 100644
--- a/can/interfaces/vector/canlib.py
+++ b/can/interfaces/vector/canlib.py
@@ -171,7 +171,7 @@ def __init__(
             )
 
         self._app_name = app_name.encode() if app_name is not None else b""
-        self.channel_info = "Application %s: %s" % (
+        self.channel_info = "Application {}: {}".format(
             app_name,
             ", ".join(f"CAN {ch + 1}" for ch in self.channels),
         )
diff --git a/can/io/canutils.py b/can/io/canutils.py
index f63df3f6b..e159ecdf4 100644
--- a/can/io/canutils.py
+++ b/can/io/canutils.py
@@ -170,7 +170,7 @@ def on_message_received(self, msg):
         if isinstance(channel, int) or isinstance(channel, str) and channel.isdigit():
             channel = f"can{channel}"
 
-        framestr = "(%f) %s" % (timestamp, channel)
+        framestr = f"({timestamp:f}) {channel}"
 
         if msg.is_error_frame:
             framestr += " %08X#" % (CAN_ERR_FLAG | CAN_ERR_BUSERROR)
diff --git a/can/io/trc.py b/can/io/trc.py
index 25ba0f5c6..0a07f01c9 100644
--- a/can/io/trc.py
+++ b/can/io/trc.py
@@ -1,5 +1,3 @@
-# coding: utf-8
-
 """
 Reader and writer for can logging files in peak trc format
 
@@ -51,7 +49,7 @@ def __init__(
                      If this is a file-like object, is has to opened in text
                      read mode, not binary read mode.
         """
-        super(TRCReader, self).__init__(file, mode="r")
+        super().__init__(file, mode="r")
         self.file_version = TRCFileVersion.UNKNOWN
 
         if not self.file:
@@ -211,7 +209,7 @@ def __init__(
         :param channel: a default channel to use when the message does not
                         have a channel set
         """
-        super(TRCWriter, self).__init__(file, mode="w")
+        super().__init__(file, mode="w")
         self.channel = channel
         if type(file) is str:
             self.filepath = os.path.abspath(file)
diff --git a/can/typechecking.py b/can/typechecking.py
index b3a513a3a..31a298995 100644
--- a/can/typechecking.py
+++ b/can/typechecking.py
@@ -11,9 +11,14 @@
 CanFilter: typing_extensions = typing_extensions.TypedDict(
     "CanFilter", {"can_id": int, "can_mask": int}
 )
-CanFilterExtended = typing_extensions.TypedDict(
-    "CanFilterExtended", {"can_id": int, "can_mask": int, "extended": bool}
-)
+
+
+class CanFilterExtended(typing_extensions.TypedDict):
+    can_id: int
+    can_mask: int
+    extended: bool
+
+
 CanFilters = typing.Sequence[typing.Union[CanFilter, CanFilterExtended]]
 
 # TODO: Once buffer protocol support lands in typing, we should switch to that,
@@ -35,8 +40,10 @@
 
 BusConfig = typing.NewType("BusConfig", typing.Dict[str, typing.Any])
 
-AutoDetectedConfig = typing_extensions.TypedDict(
-    "AutoDetectedConfig", {"interface": str, "channel": Channel}
-)
+
+class AutoDetectedConfig(typing_extensions.TypedDict):
+    interface: str
+    channel: Channel
+
 
 ReadableBytesLike = typing.Union[bytes, bytearray, memoryview]
diff --git a/can/util.py b/can/util.py
index e64eb13b5..41467542d 100644
--- a/can/util.py
+++ b/can/util.py
@@ -61,10 +61,10 @@ def load_file_config(
     else:
         config.read(path)
 
-    _config = {}
+    _config: Dict[str, str] = {}
 
     if config.has_section(section):
-        _config.update(dict((key, val) for key, val in config.items(section)))
+        _config.update(config.items(section))
 
     return _config
 
diff --git a/can/viewer.py b/can/viewer.py
index 6773a0acd..3f0376880 100644
--- a/can/viewer.py
+++ b/can/viewer.py
@@ -515,7 +515,7 @@ def parse_args(args):
     ] = {}
     if parsed_args.decode:
         if os.path.isfile(parsed_args.decode[0]):
-            with open(parsed_args.decode[0], "r", encoding="utf-8") as f:
+            with open(parsed_args.decode[0], encoding="utf-8") as f:
                 structs = f.readlines()
         else:
             structs = parsed_args.decode
diff --git a/setup.py b/setup.py
index a32471844..b3d99f612 100644
--- a/setup.py
+++ b/setup.py
@@ -15,12 +15,12 @@
 
 logging.basicConfig(level=logging.WARNING)
 
-with open("can/__init__.py", "r", encoding="utf-8") as fd:
+with open("can/__init__.py", encoding="utf-8") as fd:
     version = re.search(
         r'^__version__\s*=\s*[\'"]([^\'"]*)[\'"]', fd.read(), re.MULTILINE
     ).group(1)
 
-with open("README.rst", "r", encoding="utf-8") as f:
+with open("README.rst", encoding="utf-8") as f:
     long_description = f.read()
 
 # Dependencies
diff --git a/test/config.py b/test/config.py
index fc1bca6c2..d308a8cc8 100644
--- a/test/config.py
+++ b/test/config.py
@@ -27,7 +27,7 @@ def env(name: str) -> bool:
 IS_CI = IS_TRAVIS or IS_GITHUB_ACTIONS or env("CI") or env("CONTINUOUS_INTEGRATION")
 
 if IS_TRAVIS and IS_GITHUB_ACTIONS:
-    raise EnvironmentError(
+    raise OSError(
         f"only one of IS_TRAVIS ({IS_TRAVIS}) and IS_GITHUB_ACTIONS ({IS_GITHUB_ACTIONS}) may be True at the "
         "same time"
     )
@@ -43,7 +43,7 @@ def env(name: str) -> bool:
 del _sys
 
 if (IS_WINDOWS and IS_LINUX) or (IS_LINUX and IS_OSX) or (IS_WINDOWS and IS_OSX):
-    raise EnvironmentError(
+    raise OSError(
         f"only one of IS_WINDOWS ({IS_WINDOWS}), IS_LINUX ({IS_LINUX}) and IS_OSX ({IS_OSX}) "
         f'can be True at the same time (platform.system() == "{platform.system()}")'
     )
diff --git a/test/listener_test.py b/test/listener_test.py
index 0e64a266a..9b2e9e93b 100644
--- a/test/listener_test.py
+++ b/test/listener_test.py
@@ -88,7 +88,7 @@ def testRemoveListenerFromNotifier(self):
 
     def testPlayerTypeResolution(self):
         def test_filetype_to_instance(extension, klass):
-            print("testing: {}".format(extension))
+            print(f"testing: {extension}")
             try:
                 if extension == ".blf":
                     delete = False
@@ -123,7 +123,7 @@ def testPlayerTypeResolutionUnsupportedFileTypes(self):
 
     def testLoggerTypeResolution(self):
         def test_filetype_to_instance(extension, klass):
-            print("testing: {}".format(extension))
+            print(f"testing: {extension}")
             try:
                 with tempfile.NamedTemporaryFile(
                     suffix=extension, delete=False
diff --git a/test/logformats_test.py b/test/logformats_test.py
index 435b651b6..05c8b986f 100644
--- a/test/logformats_test.py
+++ b/test/logformats_test.py
@@ -141,7 +141,7 @@ def _setup_instance_helper(
             ]
             assert (
                 "log_event" in attrs
-            ), "cannot check comments with this writer: {}".format(writer_constructor)
+            ), f"cannot check comments with this writer: {writer_constructor}"
 
         # get all test comments
         self.original_comments = TEST_COMMENTS if check_comments else ()
diff --git a/test/message_helper.py b/test/message_helper.py
index 1e7989156..fe193097b 100644
--- a/test/message_helper.py
+++ b/test/message_helper.py
@@ -31,8 +31,8 @@ def assertMessageEqual(self, message_1, message_2):
         if message_1.equals(message_2, timestamp_delta=self.allowed_timestamp_delta):
             return
         elif self.preserves_channel:
-            print("Comparing: message 1: {!r}".format(message_1))
-            print("           message 2: {!r}".format(message_2))
+            print(f"Comparing: message 1: {message_1!r}")
+            print(f"           message 2: {message_2!r}")
             self.fail(
                 "messages are unequal with allowed timestamp delta {}".format(
                     self.allowed_timestamp_delta
@@ -46,8 +46,8 @@ def assertMessageEqual(self, message_1, message_2):
             ):
                 return
             else:
-                print("Comparing: message 1: {!r}".format(message_1))
-                print("           message 2: {!r}".format(message_2))
+                print(f"Comparing: message 1: {message_1!r}")
+                print(f"           message 2: {message_2!r}")
                 self.fail(
                     "messages are unequal with allowed timestamp delta {} even when ignoring channels".format(
                         self.allowed_timestamp_delta
diff --git a/test/test_interface_virtual.py b/test/test_interface_virtual.py
index 009722779..94833fdcb 100644
--- a/test/test_interface_virtual.py
+++ b/test/test_interface_virtual.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python
-# coding: utf-8
 
 """
 This module tests :meth:`can.interface.virtual`.
diff --git a/test/test_load_config.py b/test/test_load_config.py
index a2969b0a5..1bfba450a 100644
--- a/test/test_load_config.py
+++ b/test/test_load_config.py
@@ -30,9 +30,9 @@ def _gen_configration_file(self, sections):
         ) as tmp_config_file:
             content = []
             for section in sections:
-                content.append("[{}]".format(section))
+                content.append(f"[{section}]")
                 for k, v in self.configuration[section].items():
-                    content.append("{} = {}".format(k, v))
+                    content.append(f"{k} = {v}")
             tmp_config_file.write("\n".join(content))
             return tmp_config_file.name
 
diff --git a/test/test_load_file_config.py b/test/test_load_file_config.py
index 6b1d5a382..afedf58d4 100644
--- a/test/test_load_file_config.py
+++ b/test/test_load_file_config.py
@@ -30,9 +30,9 @@ def _gen_configration_file(self, sections):
         ) as tmp_config_file:
             content = []
             for section in sections:
-                content.append("[{}]".format(section))
+                content.append(f"[{section}]")
                 for k, v in self.configuration[section].items():
-                    content.append("{} = {}".format(k, v))
+                    content.append(f"{k} = {v}")
             tmp_config_file.write("\n".join(content))
             return tmp_config_file.name
 
diff --git a/test/test_message_class.py b/test/test_message_class.py
index 9fae7262e..4840402ff 100644
--- a/test/test_message_class.py
+++ b/test/test_message_class.py
@@ -87,8 +87,8 @@ def test_methods(self, **kwargs):
         if is_valid:
             self.assertEqual(len(message), kwargs["dlc"])
         self.assertTrue(bool(message))
-        self.assertGreater(len("{}".format(message)), 0)
-        _ = "{}".format(message)
+        self.assertGreater(len(f"{message}"), 0)
+        _ = f"{message}"
         with self.assertRaises(Exception):
             _ = "{somespec}".format(
                 message
diff --git a/test/test_message_sync.py b/test/test_message_sync.py
index 8750dd416..7552915e7 100644
--- a/test/test_message_sync.py
+++ b/test/test_message_sync.py
@@ -87,7 +87,7 @@ def test_skip(self):
 
         # the handling of the messages itself also takes some time:
         # ~0.001 s/message on a ThinkPad T560 laptop (Ubuntu 18.04, i5-6200U)
-        assert 0 < took < inc(len(messages) * (0.005 + 0.003)), "took: {}s".format(took)
+        assert 0 < took < inc(len(messages) * (0.005 + 0.003)), f"took: {took}s"
 
         self.assertMessagesEqual(messages, collected)
 
diff --git a/test/test_viewer.py b/test/test_viewer.py
index 5633a3bc1..baef10bda 100644
--- a/test/test_viewer.py
+++ b/test/test_viewer.py
@@ -302,7 +302,7 @@ def pack_data(
 
                 return struct_t.pack(*data)
         else:
-            raise ValueError("Unknown command: 0x{:02X}".format(cmd))
+            raise ValueError(f"Unknown command: 0x{cmd:02X}")
 
     def test_pack_unpack(self):
         CANOPEN_TPDO1 = 0x180