diff --git a/src/twisted/python/_setup.py b/src/twisted/python/_setup.py
index 3b5f69d4b..2dca47aa5 100644
--- a/src/twisted/python/_setup.py
+++ b/src/twisted/python/_setup.py
@@ -175,11 +175,6 @@ class ConditionalExtension(Extension, object):
 
 # The C extensions used for Twisted.
 _EXTENSIONS = [
-    ConditionalExtension(
-        "twisted.test.raiser",
-        sources=["src/twisted/test/raiser.c"],
-        condition=lambda _: _isCPython),
-
     ConditionalExtension(
         "twisted.internet.iocpreactor.iocpsupport",
         sources=[
@@ -232,7 +227,7 @@ def getSetupArgs(extensions=_EXTENSIONS):
     requirements.append("hyperlink >= 17.1.1")
 
     arguments.update(dict(
-        packages=find_packages("src"),
+        packages=find_packages("src", exclude=["*.test", "*.test.*"]),
         use_incremental=True,
         setup_requires=["incremental >= 16.10.1"],
         install_requires=requirements,
@@ -241,6 +236,7 @@ def getSetupArgs(extensions=_EXTENSIONS):
         },
         cmdclass=command_classes,
         include_package_data=True,
+        exclude_package_data={'':['test/*']},
         zip_safe=False,
         extras_require=_EXTRAS_REQUIRE,
         package_dir={"": "src"},