diff --git a/.ci/ci_lib.py b/.ci/ci_lib.py
index 65b7265a..67d20a27 100644
--- a/.ci/ci_lib.py
+++ b/.ci/ci_lib.py
@@ -193,8 +193,6 @@ class Fold(object):
     def __exit__(self, _1, _2, _3): pass
 
 
-os.environ.setdefault('ANSIBLE_STRATEGY',
-    os.environ.get('STRATEGY', 'mitogen_linear'))
 GIT_ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), '..'))
 # Used only when MODE=mitogen
 DISTRO = os.environ.get('DISTRO', 'debian9')
diff --git a/.ci/debops_common_install.py b/.ci/debops_common_install.py
index 75124fe3..afafe39a 100755
--- a/.ci/debops_common_install.py
+++ b/.ci/debops_common_install.py
@@ -7,7 +7,7 @@ ci_lib.DISTROS = ['debian']
 
 ci_lib.run_batches([
     [
-        'pip install -qqq "debops[ansible]==2.1.2"',
+        'python -m pip --no-python-version-warning --disable-pip-version-check "debops[ansible]==2.1.2"',
     ],
     [
         'aws ecr-public get-login-password | docker login --username AWS --password-stdin public.ecr.aws',
diff --git a/setup.py b/setup.py
index 9d529a36..db9595f7 100644
--- a/setup.py
+++ b/setup.py
@@ -60,7 +60,7 @@ setup(
     license = 'New BSD',
     url = 'https://github.com/mitogen-hq/mitogen/',
     packages = find_packages(exclude=['tests', 'examples']),
-    python_requires='>=2.4, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, !=3.5.*, <4',
+    python_requires='>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, !=3.5.*',
     zip_safe = False,
     classifiers = [
         'Environment :: Console',
@@ -70,10 +70,6 @@ setup(
         'Operating System :: MacOS :: MacOS X',
         'Operating System :: POSIX',
         'Programming Language :: Python',
-        'Programming Language :: Python :: 2',
-        'Programming Language :: Python :: 2.4',
-        'Programming Language :: Python :: 2.5',
-        'Programming Language :: Python :: 2.6',
         'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3',
         'Programming Language :: Python :: 3.6',
diff --git a/tests/ansible/lib/action/assert_equal.py b/tests/ansible/lib/action/assert_equal.py
index 84ec7606..f01e7ae5 100644
--- a/tests/ansible/lib/action/assert_equal.py
+++ b/tests/ansible/lib/action/assert_equal.py
@@ -11,9 +11,7 @@ import unittest2
 
 import ansible.template
 
-from ansible.errors import AnsibleError
 from ansible.plugins.action import ActionBase
-from ansible.module_utils.six import string_types
 
 
 TEMPLATE_KWARGS = {}
diff --git a/tests/ansible/mitogen_ansible_playbook.py b/tests/ansible/mitogen_ansible_playbook.py
index 54fd4283..30ed0493 100755
--- a/tests/ansible/mitogen_ansible_playbook.py
+++ b/tests/ansible/mitogen_ansible_playbook.py
@@ -1,6 +1,5 @@
 #!/usr/bin/env python
 import os
-import subprocess
 import sys
 os.environ['ANSIBLE_STRATEGY'] = 'mitogen_linear'
 os.execlp(
diff --git a/tests/bench/fork.py b/tests/bench/fork.py
index af5cb3a7..d77f4437 100644
--- a/tests/bench/fork.py
+++ b/tests/bench/fork.py
@@ -5,6 +5,12 @@ Measure latency of .fork() setup/teardown.
 import mitogen
 import mitogen.core
 
+try:
+    xrange
+except NameError:
+    xrange = range
+
+
 @mitogen.main()
 def main(router):
     t0 = mitogen.core.now()
@@ -12,4 +18,4 @@ def main(router):
         t = mitogen.core.now()
         ctx = router.fork()
         ctx.shutdown(wait=True)
-    print '++', 1000 * ((mitogen.core.now() - t0) / (1.0+x))
+    print('++ %d' % 1000 * ((mitogen.core.now() - t0) / (1.0+x)))
diff --git a/tests/create_child_test.py b/tests/create_child_test.py
index 26f10d57..aae5882d 100644
--- a/tests/create_child_test.py
+++ b/tests/create_child_test.py
@@ -6,7 +6,6 @@ import sys
 import time
 import tempfile
 
-import mock
 import unittest2
 
 import mitogen.core
@@ -80,7 +79,7 @@ def close_proc(proc):
     proc.stdin.close()
     proc.stdout.close()
     if proc.stderr:
-        prco.stderr.close()
+        proc.stderr.close()
 
 
 def wait_read(fp, n):
diff --git a/tests/data/python_never_responds.py b/tests/data/python_never_responds.py
index 449d8565..9caa5a63 100755
--- a/tests/data/python_never_responds.py
+++ b/tests/data/python_never_responds.py
@@ -1,4 +1,4 @@
-#!/usr/bin/python
+#!/usr/bin/env python
 # I am a Python interpreter that sits idle until the connection times out.
 
 import time
diff --git a/tests/parent_test.py b/tests/parent_test.py
index d6efe998..7c056f36 100644
--- a/tests/parent_test.py
+++ b/tests/parent_test.py
@@ -2,15 +2,12 @@ import errno
 import fcntl
 import os
 import signal
-import subprocess
 import sys
-import tempfile
 import time
 
 import mock
 import unittest2
 import testlib
-from testlib import Popen__terminate
 
 import mitogen.core
 import mitogen.parent
diff --git a/tests/soak/cpu_load.py b/tests/soak/cpu_load.py
index 8890272c..5a86fd0e 100644
--- a/tests/soak/cpu_load.py
+++ b/tests/soak/cpu_load.py
@@ -25,7 +25,7 @@ def burn():
 
 mul = 1.5
 count = int(mul * multiprocessing.cpu_count())
-print count
+print(count)
 
 procs = [multiprocessing.Process(target=burn)
          for _ in range(count)]
diff --git a/tests/two_three_compat_test.py b/tests/two_three_compat_test.py
index f30a233e..e761244c 100644
--- a/tests/two_three_compat_test.py
+++ b/tests/two_three_compat_test.py
@@ -1,7 +1,3 @@
-
-import logging
-import time
-
 import unittest2
 
 import mitogen.core
diff --git a/tox.ini b/tox.ini
index 43e2537e..1a0d29f9 100644
--- a/tox.ini
+++ b/tox.ini
@@ -56,10 +56,10 @@ basepython =
 deps =
     -r{toxinidir}/tests/requirements.txt
     mode_ansible: -r{toxinidir}/tests/ansible/requirements.txt
-    ansible2.3: ansible=2.3.3.0
-    ansible2.4: ansible=2.4.6.0
-    ansible2.8: ansible=2.8.3
-    ansible2.9: ansible=2.9.6
+    ansible2.3: ansible==2.3.3.0
+    ansible2.4: ansible==2.4.6.0
+    ansible2.8: ansible==2.8.3
+    ansible2.9: ansible==2.9.6
     ansible2.10: ansible-base<2.10.14
     ansible2.10: ansible==2.10.0
     ansible3: ansible-base<2.10.14
@@ -67,7 +67,7 @@ deps =
     ansible4: ansible==4.8.0
     ansible5: ansible==5.0.1
 install_command =
-    python -m pip --no-python-version-warning install {opts} {packages}
+    python -m pip --no-python-version-warning --disable-pip-version-check install {opts} {packages}
 commands_pre =
     mode_ansible: {toxinidir}/.ci/ansible_install.py
     mode_debops_common: {toxinidir}/.ci/debops_common_install.py
@@ -85,6 +85,8 @@ passenv =
     AWS_SECRET_ACCESS_KEY
     HOME
 setenv =
+    ANSIBLE_SKIP_TAGS = requires_local_sudo,resource_intensive
+    ANSIBLE_STRATEGY = mitogen_linear
     NOCOVERAGE_ERASE = 1
     NOCOVERAGE_REPORT = 1
     # Only applicable to MODE=mitogen
@@ -115,7 +117,7 @@ setenv =
     mode_ansible: MODE=ansible
     mode_debops_common: MODE=debops_common
     mode_mitogen: MODE=mitogen
-    strategy_linear: STRATEGY=linear
+    strategy_linear: ANSIBLE_STRATEGY=linear
 whitelist_externals =
     docker
     docker-credential-secretservice