diff --git a/cibuildwheel/environment.py b/cibuildwheel/environment.py
index 1b2adec4..5d548f57 100644
--- a/cibuildwheel/environment.py
+++ b/cibuildwheel/environment.py
@@ -41,7 +41,7 @@ def split_env_items(env_string):
     return result
 
 
-class EnvironmentAssignment(object):
+class EnvironmentAssignment:
     def __init__(self, assignment):
         name, equals, value = assignment.partition('=')
         if not equals:
@@ -60,7 +60,7 @@ class EnvironmentAssignment(object):
         return '%s=%s' % (self.name, self.value)
 
 
-class ParsedEnvironment(object):
+class ParsedEnvironment:
     def __init__(self, assignments):
         self.assignments = assignments
 
diff --git a/cibuildwheel/util.py b/cibuildwheel/util.py
index 14839ba3..fbee1728 100644
--- a/cibuildwheel/util.py
+++ b/cibuildwheel/util.py
@@ -23,7 +23,7 @@ def get_build_verbosity_extra_flags(level):
         return []
 
 
-class BuildSelector(object):
+class BuildSelector:
     def __init__(self, build_config, skip_config):
         self.build_patterns = build_config.split()
         self.skip_patterns = skip_config.split()
@@ -38,7 +38,7 @@ class BuildSelector(object):
 
 
 # Taken from https://stackoverflow.com/a/107717
-class Unbuffered(object):
+class Unbuffered:
     def __init__(self, stream):
         self.stream = stream
 
diff --git a/unit_test/main_util_fixtures.py b/unit_test/main_util_fixtures.py
index 3c993b35..21a7f36a 100644
--- a/unit_test/main_util_fixtures.py
+++ b/unit_test/main_util_fixtures.py
@@ -7,7 +7,7 @@ import subprocess
 from cibuildwheel import linux, macos, windows, util
 
 
-class ArgsInterceptor(object):
+class ArgsInterceptor:
     def __call__(self, *args, **kwargs):
         self.args = args
         self.kwargs = kwargs