diff --git a/dom/bindings/mozwebidlcodegen/test/test_mozwebidlcodegen.py b/dom/bindings/mozwebidlcodegen/test/test_mozwebidlcodegen.py
index 10129022e686..a2202f7b249d 100644
--- a/dom/bindings/mozwebidlcodegen/test/test_mozwebidlcodegen.py
+++ b/dom/bindings/mozwebidlcodegen/test/test_mozwebidlcodegen.py
@@ -2,7 +2,6 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-import imp
 import io
 import json
 import os
@@ -12,7 +11,7 @@ import tempfile
 import unittest
 
 import mozpack.path as mozpath
-from mozfile import NamedTemporaryFile
+from mozfile import NamedTemporaryFile, load_source
 from mozunit import MockedOpen, main
 from mozwebidlcodegen import WebIDLCodegenManager, WebIDLCodegenManagerState
 
@@ -242,7 +241,7 @@ class TestWebIDLCodegenManager(unittest.TestCase):
         with NamedTemporaryFile("wt") as fh:
             fh.write("# Original content")
             fh.flush()
-            mod = imp.load_source("mozwebidlcodegen.fakemodule", fh.name)
+            mod = load_source("mozwebidlcodegen.fakemodule", fh.name)
             mod.__file__ = fake_path
 
             args = self._get_manager_args()
diff --git a/netwerk/dns/prepare_tlds.py b/netwerk/dns/prepare_tlds.py
index 53d0bf526d3a..adebcec48705 100644
--- a/netwerk/dns/prepare_tlds.py
+++ b/netwerk/dns/prepare_tlds.py
@@ -4,11 +4,10 @@
 
 import codecs
 import encodings.idna
-import imp
-import os
 import re
 import sys
-from make_dafsa import words_to_cxx, words_to_bin
+
+from make_dafsa import words_to_bin, words_to_cxx
 
 """
 Processes a file containing effective TLD data.  See the following URL for a
@@ -22,7 +21,6 @@ http://wiki.mozilla.org/Gecko:Effective_TLD_Service
 
 def getEffectiveTLDs(path):
     file = codecs.open(path, "r", "UTF-8")
-    entries = []
     domains = set()
     for line in file:
         # line always contains a line terminator unless the file is empty
diff --git a/python/mach/mach/command_util.py b/python/mach/mach/command_util.py
index c4852570e061..052d40a0fcfb 100644
--- a/python/mach/mach/command_util.py
+++ b/python/mach/mach/command_util.py
@@ -5,13 +5,15 @@
 import argparse
 import ast
 import errno
-import imp
 import sys
+import types
 import uuid
 from collections.abc import Iterable
 from pathlib import Path
 from typing import Dict, Optional, Union
 
+from mozfile import load_source
+
 from .base import MissingFileError
 
 INVALID_ENTRY_POINT = r"""
@@ -411,13 +413,13 @@ def load_commands_from_file(path: Union[str, Path], module_name=None):
         # Ensure parent module is present otherwise we'll (likely) get
         # an error due to unknown parent.
         if "mach.commands" not in sys.modules:
-            mod = imp.new_module("mach.commands")
+            mod = types.ModuleType("mach.commands")
             sys.modules["mach.commands"] = mod
 
         module_name = f"mach.commands.{uuid.uuid4().hex}"
 
     try:
-        imp.load_source(module_name, str(path))
+        load_source(module_name, str(path))
     except IOError as e:
         if e.errno != errno.ENOENT:
             raise
diff --git a/python/mach/mach/test/test_entry_point.py b/python/mach/mach/test/test_entry_point.py
index 1129eba476c9..11aa083cda18 100644
--- a/python/mach/mach/test/test_entry_point.py
+++ b/python/mach/mach/test/test_entry_point.py
@@ -1,8 +1,8 @@
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
-import imp
 import sys
+import types
 from pathlib import Path
 from unittest.mock import patch
 
@@ -38,7 +38,7 @@ class TestEntryPoints(TestBase):
         # Ensure parent module is present otherwise we'll (likely) get
         # an error due to unknown parent.
         if "mach.commands" not in sys.modules:
-            mod = imp.new_module("mach.commands")
+            mod = types.ModuleType("mach.commands")
             sys.modules["mach.commands"] = mod
 
         mock.return_value = [Entry([self.provider_dir])]
diff --git a/python/mozbuild/mozbuild/mach_commands.py b/python/mozbuild/mozbuild/mach_commands.py
index d75fdf059c98..e54b77042286 100644
--- a/python/mozbuild/mozbuild/mach_commands.py
+++ b/python/mozbuild/mozbuild/mach_commands.py
@@ -28,6 +28,7 @@ from mach.decorators import (
     SettingsProvider,
     SubCommand,
 )
+from mozfile import load_source
 
 import mozbuild.settings  # noqa need @SettingsProvider hook to execute
 from mozbuild.base import (
@@ -1115,11 +1116,10 @@ def android_gtest(
 
     # run gtest via remotegtests.py
     exit_code = 0
-    import imp
 
     path = os.path.join("testing", "gtest", "remotegtests.py")
-    with open(path, "r") as fh:
-        imp.load_module("remotegtests", fh, path, (".py", "r", imp.PY_SOURCE))
+    load_source("remotegtests", path)
+
     import remotegtests
 
     tester = remotegtests.RemoteGTests()
diff --git a/testing/marionette/harness/marionette_harness/marionette_test/testcases.py b/testing/marionette/harness/marionette_harness/marionette_test/testcases.py
index f1b3233850c6..009e701f2d05 100644
--- a/testing/marionette/harness/marionette_harness/marionette_test/testcases.py
+++ b/testing/marionette/harness/marionette_harness/marionette_test/testcases.py
@@ -2,7 +2,7 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-import imp
+
 import os
 import re
 import sys
@@ -14,6 +14,7 @@ from unittest.case import SkipTest
 
 import six
 from marionette_driver.errors import TimeoutException, UnresponsiveInstanceException
+from mozfile import load_source
 from mozlog import get_default_logger
 
 
@@ -363,21 +364,20 @@ class MarionetteTestCase(CommonTestCase):
         testvars,
         **kwargs
     ):
-        # since we use imp.load_source to load test modules, if a module
-        # is loaded with the same name as another one the module would just be
-        # reloaded.
+        # since load_source caches modules, if a module is loaded with the same
+        # name as another one the module would just be reloaded.
         #
-        # We may end up by finding too many test in a module then since
-        # reload() only update the module dict (so old keys are still there!)
-        # see https://docs.python.org/2/library/functions.html#reload
+        # We may end up by finding too many test in a module then since reload()
+        # only update the module dict (so old keys are still there!) see
+        # https://docs.python.org/2/library/functions.html#reload
         #
-        # we get rid of that by removing the module from sys.modules,
-        # so we ensure that it will be fully loaded by the
-        # imp.load_source call.
+        # we get rid of that by removing the module from sys.modules, so we
+        # ensure that it will be fully loaded by the imp.load_source call.
+
         if mod_name in sys.modules:
             del sys.modules[mod_name]
 
-        test_mod = imp.load_source(mod_name, filepath)
+        test_mod = load_source(mod_name, filepath)
 
         for name in dir(test_mod):
             obj = getattr(test_mod, name)
diff --git a/testing/mochitest/mach_commands.py b/testing/mochitest/mach_commands.py
index f719da42061f..7ec7dcbb0a2c 100644
--- a/testing/mochitest/mach_commands.py
+++ b/testing/mochitest/mach_commands.py
@@ -14,6 +14,7 @@ import six
 from mach.decorators import Command, CommandArgument
 from mozbuild.base import MachCommandConditions as conditions
 from mozbuild.base import MozbuildObject
+from mozfile import load_source
 
 here = os.path.abspath(os.path.dirname(__file__))
 
@@ -90,11 +91,8 @@ class MochitestRunner(MozbuildObject):
         """Runs a mochitest."""
         # runtests.py is ambiguous, so we load the file/module manually.
         if "mochitest" not in sys.modules:
-            import imp
-
             path = os.path.join(self.mochitest_dir, "runtests.py")
-            with open(path, "r") as fh:
-                imp.load_module("mochitest", fh, path, (".py", "r", imp.PY_SOURCE))
+            load_source("mochitest", path)
 
         import mochitest
 
@@ -145,11 +143,9 @@ class MochitestRunner(MozbuildObject):
         if host_ret != 0:
             return host_ret
 
-        import imp
-
         path = os.path.join(self.mochitest_dir, "runtestsremote.py")
-        with open(path, "r") as fh:
-            imp.load_module("runtestsremote", fh, path, (".py", "r", imp.PY_SOURCE))
+        load_source("runtestsremote", path)
+
         import runtestsremote
 
         options = Namespace(**kwargs)
@@ -190,14 +186,11 @@ def setup_argument_parser():
     with warnings.catch_warnings():
         warnings.simplefilter("ignore")
 
-        import imp
-
         path = os.path.join(build_obj.topobjdir, mochitest_dir, "runtests.py")
         if not os.path.exists(path):
             path = os.path.join(here, "runtests.py")
 
-        with open(path, "r") as fh:
-            imp.load_module("mochitest", fh, path, (".py", "r", imp.PY_SOURCE))
+        load_source("mochitest", path)
 
         from mochitest_options import MochitestArgumentParser
 
@@ -232,14 +225,11 @@ def setup_junit_argument_parser():
         warnings.simplefilter("ignore")
 
         # runtests.py contains MochitestDesktop, required by runjunit
-        import imp
-
         path = os.path.join(build_obj.topobjdir, mochitest_dir, "runtests.py")
         if not os.path.exists(path):
             path = os.path.join(here, "runtests.py")
 
-        with open(path, "r") as fh:
-            imp.load_module("mochitest", fh, path, (".py", "r", imp.PY_SOURCE))
+        load_source("mochitest", path)
 
         import runjunit
         from mozrunner.devices.android_device import (
diff --git a/testing/mozbase/mozfile/mozfile/mozfile.py b/testing/mozbase/mozfile/mozfile/mozfile.py
index 923e38a86acc..892f8ee20f49 100644
--- a/testing/mozbase/mozfile/mozfile/mozfile.py
+++ b/testing/mozbase/mozfile/mozfile/mozfile.py
@@ -22,6 +22,7 @@ __all__ = [
     "extract",
     "is_url",
     "load",
+    "load_source",
     "copy_contents",
     "match",
     "move",
@@ -632,6 +633,19 @@ def load(resource):
     return urllib.request.urlopen(resource)
 
 
+# see https://docs.python.org/3/whatsnew/3.12.html#imp
+def load_source(modname, filename):
+    import importlib.machinery
+    import importlib.util
+
+    loader = importlib.machinery.SourceFileLoader(modname, filename)
+    spec = importlib.util.spec_from_file_location(modname, filename, loader=loader)
+    module = importlib.util.module_from_spec(spec)
+    sys.modules[module.__name__] = module
+    loader.exec_module(module)
+    return module
+
+
 # We can't depend on mozpack.path here, so copy the 'match' function over.
 
 re_cache = {}
diff --git a/testing/mozharness/scripts/desktop_unittest.py b/testing/mozharness/scripts/desktop_unittest.py
index 1aaa0803d862..38b807ccfe37 100755
--- a/testing/mozharness/scripts/desktop_unittest.py
+++ b/testing/mozharness/scripts/desktop_unittest.py
@@ -12,7 +12,6 @@ author: Jordan Lund
 
 import copy
 import glob
-import imp
 import json
 import multiprocessing
 import os
@@ -25,6 +24,7 @@ from datetime import datetime, timedelta
 here = os.path.abspath(os.path.dirname(__file__))
 sys.path.insert(1, os.path.dirname(here))
 
+from mozfile import load_source
 from mozharness.base.errors import BaseErrorList
 from mozharness.base.log import INFO, WARNING
 from mozharness.base.script import PreScriptAction
@@ -1198,7 +1198,7 @@ class DesktopUnittest(TestingMixin, MercurialScript, MozbaseMixin, CodeCoverageM
                 )
 
                 if suite_category == "reftest":
-                    ref_formatter = imp.load_source(
+                    ref_formatter = load_source(
                         "ReftestFormatter",
                         os.path.abspath(
                             os.path.join(dirs["abs_reftest_dir"], "output.py")
diff --git a/testing/web-platform/manifestupdate.py b/testing/web-platform/manifestupdate.py
index 79b7f1ae5693..f8f9d08cb993 100644
--- a/testing/web-platform/manifestupdate.py
+++ b/testing/web-platform/manifestupdate.py
@@ -5,13 +5,13 @@
 import argparse
 import errno
 import hashlib
-import imp
 import os
 import sys
 
 import manifestdownload
 import six
 from mach.util import get_state_dir
+from mozfile import load_source
 from mozlog.structured import commandline
 from six.moves import configparser
 from wptrunner import wptcommandline
@@ -21,9 +21,7 @@ manifest = None
 
 def do_delayed_imports(wpt_dir):
     global manifest
-    imp.load_source(
-        "localpaths", os.path.join(wpt_dir, "tests", "tools", "localpaths.py")
-    )
+    load_source("localpaths", os.path.join(wpt_dir, "tests", "tools", "localpaths.py"))
     sys.path.insert(0, os.path.join(wpt_dir, "tools", "manifest"))
     import manifest
 
diff --git a/testing/web-platform/tests/service-workers/service-worker/resources/scope1/redirect.py b/testing/web-platform/tests/service-workers/service-worker/resources/scope1/redirect.py
index bb4c874aacee..025ea671c503 100644
--- a/testing/web-platform/tests/service-workers/service-worker/resources/scope1/redirect.py
+++ b/testing/web-platform/tests/service-workers/service-worker/resources/scope1/redirect.py
@@ -1,6 +1,8 @@
 import os
-import imp
+
+from tools.wpt.utils import load_source
+
 # Use the file from the parent directory.
-mod = imp.load_source("_parent", os.path.join(os.path.dirname(os.path.dirname(__file__)),
+mod = load_source("_parent", os.path.join(os.path.dirname(os.path.dirname(__file__)),
                                               os.path.basename(__file__)))
 main = mod.main
diff --git a/testing/web-platform/tests/service-workers/service-worker/resources/scope2/worker_interception_redirect_webworker.py b/testing/web-platform/tests/service-workers/service-worker/resources/scope2/worker_interception_redirect_webworker.py
index bb4c874aacee..025ea671c503 100644
--- a/testing/web-platform/tests/service-workers/service-worker/resources/scope2/worker_interception_redirect_webworker.py
+++ b/testing/web-platform/tests/service-workers/service-worker/resources/scope2/worker_interception_redirect_webworker.py
@@ -1,6 +1,8 @@
 import os
-import imp
+
+from tools.wpt.utils import load_source
+
 # Use the file from the parent directory.
-mod = imp.load_source("_parent", os.path.join(os.path.dirname(os.path.dirname(__file__)),
+mod = load_source("_parent", os.path.join(os.path.dirname(os.path.dirname(__file__)),
                                               os.path.basename(__file__)))
 main = mod.main
diff --git a/testing/web-platform/tests/service-workers/service-worker/resources/subdir/worker_interception_redirect_webworker.py b/testing/web-platform/tests/service-workers/service-worker/resources/subdir/worker_interception_redirect_webworker.py
index bb4c874aacee..025ea671c503 100644
--- a/testing/web-platform/tests/service-workers/service-worker/resources/subdir/worker_interception_redirect_webworker.py
+++ b/testing/web-platform/tests/service-workers/service-worker/resources/subdir/worker_interception_redirect_webworker.py
@@ -1,6 +1,8 @@
 import os
-import imp
+
+from tools.wpt.utils import load_source
+
 # Use the file from the parent directory.
-mod = imp.load_source("_parent", os.path.join(os.path.dirname(os.path.dirname(__file__)),
+mod = load_source("_parent", os.path.join(os.path.dirname(os.path.dirname(__file__)),
                                               os.path.basename(__file__)))
 main = mod.main
diff --git a/testing/web-platform/tests/tools/runner/update_manifest.py b/testing/web-platform/tests/tools/runner/update_manifest.py
index a7f72b35b339..58b9ac4d84bf 100644
--- a/testing/web-platform/tests/tools/runner/update_manifest.py
+++ b/testing/web-platform/tests/tools/runner/update_manifest.py
@@ -1,16 +1,18 @@
 # mypy: ignore-errors
 
-import imp
 import json
 import os
 
+from tools.wpt.utils import load_source
+
 here = os.path.dirname(__file__)
-localpaths = imp.load_source("localpaths", os.path.abspath(os.path.join(here, os.pardir, "localpaths.py")))
+localpaths = load_source("localpaths", os.path.abspath(os.path.join(here, os.pardir, "localpaths.py")))
 
 root = localpaths.repo_root
 
 from manifest import manifest
 
+
 def main(request, response):
     path = os.path.join(root, "MANIFEST.json")
 
diff --git a/testing/web-platform/tests/tools/wpt/utils.py b/testing/web-platform/tests/tools/wpt/utils.py
index b015b95e1ae2..5899dc3f3a96 100644
--- a/testing/web-platform/tests/tools/wpt/utils.py
+++ b/testing/web-platform/tests/tools/wpt/utils.py
@@ -3,10 +3,10 @@
 import errno
 import logging
 import os
-import sys
 import shutil
 import stat
 import subprocess
+import sys
 import tarfile
 import time
 import zipfile
@@ -166,3 +166,16 @@ def sha256sum(file_path):
         for chunk in iter(lambda: f.read(4096), b''):
             hash.update(chunk)
     return hash.hexdigest()
+
+
+# see https://docs.python.org/3/whatsnew/3.12.html#imp
+def load_source(modname, filename):
+    import importlib.machinery
+    import importlib.util
+
+    loader = importlib.machinery.SourceFileLoader(modname, filename)
+    spec = importlib.util.spec_from_file_location(modname, filename, loader=loader)
+    module = importlib.util.module_from_spec(spec)
+    sys.modules[module.__name__] = module
+    loader.exec_module(module)
+    return module
diff --git a/testing/web-platform/tests/tools/wptrunner/wptrunner/stability.py b/testing/web-platform/tests/tools/wptrunner/wptrunner/stability.py
index 9ac6249c44cb..1f17ef3c4776 100644
--- a/testing/web-platform/tests/tools/wptrunner/wptrunner/stability.py
+++ b/testing/web-platform/tests/tools/wptrunner/wptrunner/stability.py
@@ -2,7 +2,6 @@
 
 import copy
 import functools
-import imp
 import io
 import os
 from collections import OrderedDict, defaultdict
@@ -10,16 +9,17 @@ from datetime import datetime
 
 from mozlog import reader
 from mozlog.formatters import JSONFormatter
-from mozlog.handlers import BaseHandler, StreamHandler, LogLevelFilter
+from mozlog.handlers import BaseHandler, LogLevelFilter, StreamHandler
+
+from tools.wpt.utils import load_source
 
 from . import wptrunner
 
 here = os.path.dirname(__file__)
-localpaths = imp.load_source("localpaths", os.path.abspath(os.path.join(here, os.pardir, os.pardir, "localpaths.py")))
+localpaths = load_source("localpaths", os.path.abspath(os.path.join(here, os.pardir, os.pardir, "localpaths.py")))
 from ci.tc.github_checks_output import get_gh_checks_outputter  # type: ignore
 from wpt.markdown import markdown_adjust, table  # type: ignore
 
-
 # If a test takes more than (FLAKY_THRESHOLD*timeout) and does not consistently
 # time out, it is considered slow (potentially flaky).
 FLAKY_THRESHOLD = 0.8
diff --git a/testing/web-platform/tests/xhr/resources/auth1/auth.py b/testing/web-platform/tests/xhr/resources/auth1/auth.py
index db4f7bc4c9fe..3797aaa52e95 100644
--- a/testing/web-platform/tests/xhr/resources/auth1/auth.py
+++ b/testing/web-platform/tests/xhr/resources/auth1/auth.py
@@ -1,12 +1,13 @@
-import imp
 import os
 
 from wptserve.utils import isomorphic_decode
 
+from tools.wpt.utils import load_source
+
 here = os.path.dirname(os.path.abspath(isomorphic_decode(__file__)))
 
 def main(request, response):
-    auth = imp.load_source(u"", os.path.join(here,
+    auth = load_source(u"", os.path.join(here,
                                              u"..",
                                              u"authentication.py"))
     return auth.main(request, response)
diff --git a/testing/web-platform/tests/xhr/resources/auth10/auth.py b/testing/web-platform/tests/xhr/resources/auth10/auth.py
index db4f7bc4c9fe..568d31e90687 100644
--- a/testing/web-platform/tests/xhr/resources/auth10/auth.py
+++ b/testing/web-platform/tests/xhr/resources/auth10/auth.py
@@ -1,12 +1,14 @@
-import imp
 import os
 
 from wptserve.utils import isomorphic_decode
 
+from tools.wpt.utils import load_source
+
 here = os.path.dirname(os.path.abspath(isomorphic_decode(__file__)))
 
+
 def main(request, response):
-    auth = imp.load_source(u"", os.path.join(here,
+    auth = load_source(u"", os.path.join(here,
                                              u"..",
                                              u"authentication.py"))
     return auth.main(request, response)
diff --git a/testing/web-platform/tests/xhr/resources/auth11/auth.py b/testing/web-platform/tests/xhr/resources/auth11/auth.py
index db4f7bc4c9fe..3797aaa52e95 100644
--- a/testing/web-platform/tests/xhr/resources/auth11/auth.py
+++ b/testing/web-platform/tests/xhr/resources/auth11/auth.py
@@ -1,12 +1,13 @@
-import imp
 import os
 
 from wptserve.utils import isomorphic_decode
 
+from tools.wpt.utils import load_source
+
 here = os.path.dirname(os.path.abspath(isomorphic_decode(__file__)))
 
 def main(request, response):
-    auth = imp.load_source(u"", os.path.join(here,
+    auth = load_source(u"", os.path.join(here,
                                              u"..",
                                              u"authentication.py"))
     return auth.main(request, response)
diff --git a/testing/web-platform/tests/xhr/resources/auth2/auth.py b/testing/web-platform/tests/xhr/resources/auth2/auth.py
index db4f7bc4c9fe..568d31e90687 100644
--- a/testing/web-platform/tests/xhr/resources/auth2/auth.py
+++ b/testing/web-platform/tests/xhr/resources/auth2/auth.py
@@ -1,12 +1,14 @@
-import imp
 import os
 
 from wptserve.utils import isomorphic_decode
 
+from tools.wpt.utils import load_source
+
 here = os.path.dirname(os.path.abspath(isomorphic_decode(__file__)))
 
+
 def main(request, response):
-    auth = imp.load_source(u"", os.path.join(here,
+    auth = load_source(u"", os.path.join(here,
                                              u"..",
                                              u"authentication.py"))
     return auth.main(request, response)
diff --git a/testing/web-platform/tests/xhr/resources/auth2/corsenabled.py b/testing/web-platform/tests/xhr/resources/auth2/corsenabled.py
index bec6687dbe96..7b9d3b65aba2 100644
--- a/testing/web-platform/tests/xhr/resources/auth2/corsenabled.py
+++ b/testing/web-platform/tests/xhr/resources/auth2/corsenabled.py
@@ -1,8 +1,9 @@
-import imp
 import os
 
 from wptserve.utils import isomorphic_decode
 
+from tools.wpt.utils import load_source
+
 here = os.path.dirname(isomorphic_decode(__file__))
 
 def main(request, response):
@@ -11,7 +12,7 @@ def main(request, response):
     response.headers.set(b'Access-Control-Allow-Methods', b'GET')
     response.headers.set(b'Access-Control-Allow-Headers', b'authorization, x-user, x-pass')
     response.headers.set(b'Access-Control-Expose-Headers', b'x-challenge, xhr-user, ses-user')
-    auth = imp.load_source(u"", os.path.abspath(os.path.join(here, os.pardir, u"authentication.py")))
+    auth = load_source(u"", os.path.abspath(os.path.join(here, os.pardir, u"authentication.py")))
     if request.method == u"OPTIONS":
         return b""
     else:
diff --git a/testing/web-platform/tests/xhr/resources/auth3/auth.py b/testing/web-platform/tests/xhr/resources/auth3/auth.py
index db4f7bc4c9fe..3797aaa52e95 100644
--- a/testing/web-platform/tests/xhr/resources/auth3/auth.py
+++ b/testing/web-platform/tests/xhr/resources/auth3/auth.py
@@ -1,12 +1,13 @@
-import imp
 import os
 
 from wptserve.utils import isomorphic_decode
 
+from tools.wpt.utils import load_source
+
 here = os.path.dirname(os.path.abspath(isomorphic_decode(__file__)))
 
 def main(request, response):
-    auth = imp.load_source(u"", os.path.join(here,
+    auth = load_source(u"", os.path.join(here,
                                              u"..",
                                              u"authentication.py"))
     return auth.main(request, response)
diff --git a/testing/web-platform/tests/xhr/resources/auth4/auth.py b/testing/web-platform/tests/xhr/resources/auth4/auth.py
index db4f7bc4c9fe..3797aaa52e95 100644
--- a/testing/web-platform/tests/xhr/resources/auth4/auth.py
+++ b/testing/web-platform/tests/xhr/resources/auth4/auth.py
@@ -1,12 +1,13 @@
-import imp
 import os
 
 from wptserve.utils import isomorphic_decode
 
+from tools.wpt.utils import load_source
+
 here = os.path.dirname(os.path.abspath(isomorphic_decode(__file__)))
 
 def main(request, response):
-    auth = imp.load_source(u"", os.path.join(here,
+    auth = load_source(u"", os.path.join(here,
                                              u"..",
                                              u"authentication.py"))
     return auth.main(request, response)
diff --git a/testing/web-platform/tests/xhr/resources/auth7/corsenabled.py b/testing/web-platform/tests/xhr/resources/auth7/corsenabled.py
index 7a060627b70d..c82ba4e6bc45 100644
--- a/testing/web-platform/tests/xhr/resources/auth7/corsenabled.py
+++ b/testing/web-platform/tests/xhr/resources/auth7/corsenabled.py
@@ -1,8 +1,9 @@
-import imp
 import os
 
 from wptserve.utils import isomorphic_decode
 
+from tools.wpt.utils import load_source
+
 here = os.path.dirname(isomorphic_decode(__file__))
 
 def main(request, response):
@@ -11,7 +12,7 @@ def main(request, response):
     response.headers.set(b'Access-Control-Allow-Methods', b'GET')
     response.headers.set(b'Access-Control-Allow-Headers', b'authorization, x-user, x-pass')
     response.headers.set(b'Access-Control-Expose-Headers', b'x-challenge, xhr-user, ses-user')
-    auth = imp.load_source(u"", os.path.join(here,
+    auth = load_source(u"", os.path.join(here,
                                              os.pardir,
                                              u"authentication.py"))
     if request.method == u"OPTIONS":
diff --git a/testing/web-platform/tests/xhr/resources/auth8/corsenabled-no-authorize.py b/testing/web-platform/tests/xhr/resources/auth8/corsenabled-no-authorize.py
index af8e7c4c170a..4fdf99e2658c 100644
--- a/testing/web-platform/tests/xhr/resources/auth8/corsenabled-no-authorize.py
+++ b/testing/web-platform/tests/xhr/resources/auth8/corsenabled-no-authorize.py
@@ -1,8 +1,9 @@
-import imp
 import os
 
 from wptserve.utils import isomorphic_decode
 
+from tools.wpt.utils import load_source
+
 here = os.path.dirname(isomorphic_decode(__file__))
 
 def main(request, response):
@@ -11,7 +12,7 @@ def main(request, response):
     response.headers.set(b'Access-Control-Allow-Methods', b'GET')
     response.headers.set(b'Access-Control-Allow-Headers', b'x-user, x-pass')
     response.headers.set(b'Access-Control-Expose-Headers', b'x-challenge, xhr-user, ses-user')
-    auth = imp.load_source(u"", os.path.join(here,
+    auth = load_source(u"", os.path.join(here,
                                              os.pardir,
                                              u"authentication.py"))
     if request.method == u"OPTIONS":
diff --git a/testing/web-platform/tests/xhr/resources/auth9/auth.py b/testing/web-platform/tests/xhr/resources/auth9/auth.py
index db4f7bc4c9fe..3797aaa52e95 100644
--- a/testing/web-platform/tests/xhr/resources/auth9/auth.py
+++ b/testing/web-platform/tests/xhr/resources/auth9/auth.py
@@ -1,12 +1,13 @@
-import imp
 import os
 
 from wptserve.utils import isomorphic_decode
 
+from tools.wpt.utils import load_source
+
 here = os.path.dirname(os.path.abspath(isomorphic_decode(__file__)))
 
 def main(request, response):
-    auth = imp.load_source(u"", os.path.join(here,
+    auth = load_source(u"", os.path.join(here,
                                              u"..",
                                              u"authentication.py"))
     return auth.main(request, response)
diff --git a/testing/web-platform/update/__init__.py b/testing/web-platform/update/__init__.py
index 47c6d36d9507..66bb6f2ab670 100644
--- a/testing/web-platform/update/__init__.py
+++ b/testing/web-platform/update/__init__.py
@@ -4,15 +4,15 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-import imp
 import os
 import sys
 
+from mozfile import load_source
 from mozlog import structuredlog
 
 here = os.path.split(__file__)[0]
 
-imp.load_source(
+load_source(
     "localpaths", os.path.join(here, os.pardir, "tests", "tools", "localpaths.py")
 )
 
diff --git a/tools/moztreedocs/mach_commands.py b/tools/moztreedocs/mach_commands.py
index 6f44c65c209e..84bdaf79fb00 100644
--- a/tools/moztreedocs/mach_commands.py
+++ b/tools/moztreedocs/mach_commands.py
@@ -21,6 +21,7 @@ import yaml
 from mach.decorators import Command, CommandArgument, SubCommand
 from mach.registrar import Registrar
 from mozbuild.util import memoize
+from mozfile import load_source
 
 here = os.path.abspath(os.path.dirname(__file__))
 topsrcdir = os.path.abspath(os.path.dirname(os.path.dirname(here)))
@@ -363,11 +364,8 @@ def toggle_no_autodoc():
 
 @memoize
 def _read_project_properties():
-    import imp
-
     path = os.path.normpath(manager().conf_py_path)
-    with open(path, "r") as fh:
-        conf = imp.load_module("doc_conf", fh, path, (".py", "r", imp.PY_SOURCE))
+    conf = load_source("doc_conf", path)
 
     # Prefer the Mozilla project name, falling back to Sphinx's
     # default variable if it isn't defined.
diff --git a/tools/tryselect/test/test_mozharness_integration.py b/tools/tryselect/test/test_mozharness_integration.py
index 984f8de25b83..abeaaf370e77 100644
--- a/tools/tryselect/test/test_mozharness_integration.py
+++ b/tools/tryselect/test/test_mozharness_integration.py
@@ -2,12 +2,12 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
-import imp
 import json
 import os
 
 import mozunit
 import pytest
+from mozfile import load_source
 from tryselect.tasks import build, resolve_tests_by_suite
 
 MOZHARNESS_SCRIPTS = {
@@ -55,10 +55,10 @@ uses).
 
 
 def get_mozharness_test_paths(name):
-    scriptdir = os.path.join(build.topsrcdir, "testing", "mozharness", "scripts")
-
-    files = imp.find_module(name, [scriptdir])
-    mod = imp.load_module("scripts.{}".format(name), *files)
+    scriptdir = os.path.join(build.topsrcdir, "testing", "mozharness")
+    mod = load_source(
+        "scripts." + name, os.path.join(scriptdir, "scripts", name + ".py")
+    )
 
     class_name = MOZHARNESS_SCRIPTS[name]["class_name"]
     cls = getattr(mod, class_name)
@@ -82,13 +82,15 @@ def all_suites():
 
 
 def generate_suites_from_config(path):
-    configdir = os.path.join(build.topsrcdir, "testing", "mozharness", "configs")
-
     parent, name = os.path.split(path)
     name = os.path.splitext(name)[0]
 
-    files = imp.find_module("{}".format(name), [os.path.join(configdir, parent)])
-    mod = imp.load_module("config.{}".format(name), *files)
+    configdir = os.path.join(
+        build.topsrcdir, "testing", "mozharness", "configs", parent
+    )
+
+    mod = load_source(name, os.path.join(configdir, name + ".py"))
+
     config = mod.config
 
     for category in sorted(config["suite_definitions"]):