diff --git a/cpplint.py b/cpplint.py
index 6556c97..f9edf3c 100755
--- a/cpplint.py
+++ b/cpplint.py
@@ -1214,7 +1214,7 @@ def _IsSourceExtension(s):
     return s in GetNonHeaderExtensions()
 
 
-class _IncludeState(object):
+class _IncludeState:
     """Tracks line numbers for includes, and the order in which includes appear.
 
     include_list contains list of lists of (header, line number) pairs.
@@ -1392,7 +1392,7 @@ def CheckNextIncludeOrder(self, header_type):
         return ""
 
 
-class _CppLintState(object):
+class _CppLintState:
     """Maintains module-wide state.."""
 
     def __init__(self):
@@ -1637,7 +1637,7 @@ def _RestoreFilters():
     _cpplint_state.RestoreFilters()
 
 
-class _FunctionState(object):
+class _FunctionState:
     """Tracks current function name and the number of lines in its body."""
 
     _NORMAL_TRIGGER = 250  # for --v=0, 500 for --v=1, etc.
@@ -1705,7 +1705,7 @@ class _IncludeError(Exception):
     pass
 
 
-class FileInfo(object):
+class FileInfo:
     """Provides utility functions for filenames.
 
     FileInfo provides easy access to the components of a file's path
@@ -2104,7 +2104,7 @@ def ReplaceAlternateTokens(line):
     return line
 
 
-class CleansedLines(object):
+class CleansedLines:
     """Holds 4 copies of all lines with different preprocessing applied to them.
 
     1) elided member contains lines without strings and comments.
@@ -2973,7 +2973,7 @@ def IsForwardClassDeclaration(clean_lines, linenum):
     return re.match(r"^\s*(\btemplate\b)*.*class\s+\w+;\s*$", clean_lines[linenum])
 
 
-class _BlockInfo(object):
+class _BlockInfo:
     """Stores information about a generic block of code."""
 
     def __init__(self, linenum, seen_open_brace):
@@ -3188,7 +3188,7 @@ def CheckEnd(self, filename, clean_lines, linenum, error):
                     )
 
 
-class _PreprocessorInfo(object):
+class _PreprocessorInfo:
     """Stores checkpoints of nesting stacks when #if/#else is seen."""
 
     def __init__(self, stack_before_if):
@@ -3202,7 +3202,7 @@ def __init__(self, stack_before_if):
         self.seen_else = False
 
 
-class NestingState(object):
+class NestingState:
     """Holds states related to parsing braces."""
 
     def __init__(self):
@@ -7417,7 +7417,7 @@ def ProcessConfigOverrides(filename):
                             f"Invalid configuration option ({name}) in file {cfg_file}\n"
                         )
 
-        except IOError:
+        except OSError:
             _cpplint_state.PrintError(
                 f"Skipping config file '{cfg_file}': Can't open for reading\n"
             )
@@ -7478,7 +7478,7 @@ def ProcessFile(filename, vlevel, extra_check_functions=None):
             else:
                 lf_lines.append(linenum + 1)
 
-    except IOError:
+    except OSError:
         # TODO: Maybe make this have an exit code of 2 after all is done
         _cpplint_state.PrintError(f"Skipping input '{filename}': Can't open for reading\n")
         _RestoreFilters()
diff --git a/cpplint_clitest.py b/cpplint_clitest.py
index f20d54d..75a9733 100755
--- a/cpplint_clitest.py
+++ b/cpplint_clitest.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python
-# -*- coding: utf-8; -*-
 #
 # Copyright (c) 2009 Google Inc. All rights reserved.
 #
@@ -162,8 +161,8 @@ def _run_and_compare(self, definition_file, args, expected_status, expected_out,
         # command to reproduce, do not forget first two lines have special meaning
         print("\ncd " + cwd + " && " + cmd + " " + args + " 2> <filename>")
         (status, out, err) = run_shell_command(cmd, args, cwd)
-        self.assertEqual(expected_status, status, "bad command status %s" % status)
-        prefix = "Failed check in %s comparing to %s for command: %s" % (cwd, definition_file, cmd)
+        self.assertEqual(expected_status, status, f"bad command status {status}")
+        prefix = f"Failed check in {cwd} comparing to {definition_file} for command: {cmd}"
         compare("\n".join(expected_err), err.decode("utf8"), prefix=prefix, show_whitespace=True)
         compare("\n".join(expected_out), out.decode("utf8"), prefix=prefix, show_whitespace=True)
 
diff --git a/cpplint_unittest.py b/cpplint_unittest.py
index 33d3fc8..bae157d 100755
--- a/cpplint_unittest.py
+++ b/cpplint_unittest.py
@@ -1,5 +1,4 @@
 #!/usr/bin/env python
-# -*- coding: utf-8; -*-
 #
 # Copyright (c) 2009 Google Inc. All rights reserved.
 #
@@ -51,15 +50,13 @@
 
 
 def codecs_latin_encode(x):
-    if sys.version_info < (3,):
-        return x
     return codecs.latin_1_encode(x)[0]
 
 
 # This class works as an error collector and replaces cpplint.Error
 # function for the unit tests.  We also verify each category we see
 # is in cpplint._ERROR_CATEGORIES, to help keep that list up to date.
-class ErrorCollector(object):
+class ErrorCollector:
     # These are a global list, covering all categories seen ever.
     _ERROR_CATEGORIES = cpplint._ERROR_CATEGORIES
     _SEEN_ERROR_CATEGORIES = {}
@@ -110,7 +107,7 @@ def RemoveIfPresent(self, substr):
 
 # This class is a lame mock of codecs. We do not verify filename, mode, or
 # encoding, but for the current use case it is not needed.
-class MockIo(object):
+class MockIo:
     def __init__(self, mock_file):
         # wrap list to allow "with open(mock)"
         class EnterableList(list):
@@ -357,7 +354,7 @@ def testNestingInNamespace(self):
     # Test get line width.
     def testGetLineWidth(self):
         self.assertEqual(0, cpplint.GetLineWidth(""))
-        self.assertEqual(10, cpplint.GetLineWidth(str("x") * 10))
+        self.assertEqual(10, cpplint.GetLineWidth("x" * 10))
         self.assertEqual(16, cpplint.GetLineWidth("\u90fd|\u9053|\u5e9c|\u770c|\u652f\u5e81"))
         self.assertEqual(16, cpplint.GetLineWidth("都|道|府|県|支庁"))
         self.assertEqual(5 + 13 + 9, cpplint.GetLineWidth("d𝐱/dt" + "f : t ⨯ 𝐱 → ℝ" + "t ⨯ 𝐱 → ℝ"))
@@ -1056,21 +1053,17 @@ def testMockMethod(self):
         self.assertEqual(
             0,
             error_collector.Results().count(
-                (
-                    "Using deprecated casting style.  "
-                    "Use static_cast<bool>(...) instead  "
-                    "[readability/casting] [4]"
-                )
+                "Using deprecated casting style.  "
+                "Use static_cast<bool>(...) instead  "
+                "[readability/casting] [4]"
             ),
         )
         self.assertEqual(
             1,
             error_collector.Results().count(
-                (
-                    "Using deprecated casting style.  "
-                    "Use static_cast<int>(...) instead  "
-                    "[readability/casting] [4]"
-                )
+                "Using deprecated casting style.  "
+                "Use static_cast<int>(...) instead  "
+                "[readability/casting] [4]"
             ),
         )
 
@@ -4842,9 +4835,7 @@ def testRecursiveExclude(self):
 
             expected = [os.path.join("src", "one.cc")]
             cpplint._excludes = None
-            actual = cpplint.ParseArguments(
-                ["--recursive", "--exclude=src{0}t*".format(os.sep), "src"]
-            )
+            actual = cpplint.ParseArguments(["--recursive", f"--exclude=src{os.sep}t*", "src"])
             self.assertEqual(set(expected), set(actual))
 
             expected = [os.path.join("src", "one.cc")]
diff --git a/pyproject.toml b/pyproject.toml
index 951958b..641c92c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -103,6 +103,7 @@ lint.select = [
   "TC",    # flake8-type-checking
   "TID",   # flake8-tidy-imports
   "TRY",   # tryceratops
+  "UP",    # pyupgrade
   "W",     # pycodestyle
   "YTT",   # flake8-2020
   # "ANN", # flake8-annotations
@@ -124,7 +125,6 @@ lint.select = [
   # "SLF", # flake8-self
   # "T20", # flake8-print
   # "TD",  # flake8-todos
-  # "UP",  # pyupgrade
 ]
 lint.ignore = [
   "FBT003", # flake8-boolean-trap
@@ -133,7 +133,7 @@ lint.ignore = [
   "PIE790", # Unnecessary `pass` statement
 ]
 lint.per-file-ignores."cpplint.py" = [ "ICN001", "PERF401", "PLR5501", "PLW0603", "PLW2901" ]
-lint.per-file-ignores."cpplint_unittest.py" = [ "FLY002", "PLW0604" ]
+lint.per-file-ignores."cpplint_unittest.py" = [ "FLY002", "PLW0604", "UP031" ]
 lint.mccabe.max-complexity = 29
 lint.pylint.allow-magic-value-types = [ "int", "str" ]
 lint.pylint.max-args = 10 # Default is 5
@@ -145,13 +145,13 @@ lint.pylint.max-returns = 9 # Default is 9
 lint.pylint.max-statements = 74 # Default is 50
 
 [tool.pylint.basic]
+argument-rgx = "[a-z_][a-z0-9_]{0,49}$"
+class-rgx = "[A-Z_][a-zA-Z0-9]+$"
+const-rgx = "[a-zA-Z_][A-Za-z0-9_]{2,49}$"
+function-rgx = "[A-Z_][A-Za-z0-9]{2,49}$|main"
 include-naming-hint = true
 method-rgx = "[A-Z_][A-Za-z0-9]{2,49}$|__init__|__str__|__contains__"
-function-rgx = "[A-Z_][A-Za-z0-9]{2,49}$|main"
-const-rgx = "[a-zA-Z_][A-Za-z0-9_]{2,49}$"
 variable-rgx = "[a-z_][a-z0-9_]{0,49}$"
-argument-rgx = "[a-z_][a-z0-9_]{0,49}$"
-class-rgx = "[A-Z_][a-zA-Z0-9]+$"
 
 [tool.pylint.messages-control]
 disable = [
@@ -180,25 +180,25 @@ reports = false
 score = false
 
 [tool.pylint.format]
-indent-string = '    '
 indent-after-paren = 4
+indent-string = '    '
 max-module-lines = 10000
 
 [tool.pylint.design]
-max-locals = 25
-max-line-length = 100
+max-args = 20
 max-attributes = 10
+max-bool-expr = 10
 max-branches = 30
-max-args = 20
-max-statements = 75
+max-line-length = 100
+max-locals = 25
 max-returns = 10
+max-statements = 75
 min-public-methods = 0
-max-bool-expr = 10
 
 [tool.pytest.ini_options]
+# fail if coverage is under 90%
+addopts = "--color=yes --cov-fail-under=90 --cov=cpplint"
 python_files = [ "*test.py" ]
-testpaths = [ "." ]
 required_plugins = [ "pytest-cov", "pytest-timeout" ]
+testpaths = [ "." ]
 timeout = 60
-# fail if coverage is under 90%
-addopts = "--color=yes --cov-fail-under=90 --cov=cpplint"