diff --git a/setup.py b/setup.py
index 8b9617d..9afe94a 100644
--- a/setup.py
+++ b/setup.py
@@ -3,10 +3,13 @@
 from __future__ import with_statement
 
 import functools
+import os
 import sys
 
 import setuptools
 
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), 'src'))
+
 import flake8  # noqa
 
 try:
@@ -66,6 +69,7 @@ setuptools.setup(
     maintainer="Ian Cordasco",
     maintainer_email="graffatcolmingov@gmail.com",
     url="https://gitlab.com/pycqa/flake8",
+    package_dir={"": "src"},
     packages=[
         "flake8",
         "flake8.api",
diff --git a/flake8/__init__.py b/src/flake8/__init__.py
similarity index 100%
rename from flake8/__init__.py
rename to src/flake8/__init__.py
diff --git a/flake8/__main__.py b/src/flake8/__main__.py
similarity index 100%
rename from flake8/__main__.py
rename to src/flake8/__main__.py
diff --git a/flake8/api/__init__.py b/src/flake8/api/__init__.py
similarity index 100%
rename from flake8/api/__init__.py
rename to src/flake8/api/__init__.py
diff --git a/flake8/checker.py b/src/flake8/checker.py
similarity index 100%
rename from flake8/checker.py
rename to src/flake8/checker.py
diff --git a/flake8/defaults.py b/src/flake8/defaults.py
similarity index 100%
rename from flake8/defaults.py
rename to src/flake8/defaults.py
diff --git a/flake8/exceptions.py b/src/flake8/exceptions.py
similarity index 100%
rename from flake8/exceptions.py
rename to src/flake8/exceptions.py
diff --git a/flake8/formatting/__init__.py b/src/flake8/formatting/__init__.py
similarity index 100%
rename from flake8/formatting/__init__.py
rename to src/flake8/formatting/__init__.py
diff --git a/flake8/formatting/base.py b/src/flake8/formatting/base.py
similarity index 100%
rename from flake8/formatting/base.py
rename to src/flake8/formatting/base.py
diff --git a/flake8/formatting/default.py b/src/flake8/formatting/default.py
similarity index 100%
rename from flake8/formatting/default.py
rename to src/flake8/formatting/default.py
diff --git a/flake8/main/__init__.py b/src/flake8/main/__init__.py
similarity index 100%
rename from flake8/main/__init__.py
rename to src/flake8/main/__init__.py
diff --git a/flake8/main/application.py b/src/flake8/main/application.py
similarity index 100%
rename from flake8/main/application.py
rename to src/flake8/main/application.py
diff --git a/flake8/main/cli.py b/src/flake8/main/cli.py
similarity index 100%
rename from flake8/main/cli.py
rename to src/flake8/main/cli.py
diff --git a/flake8/main/git.py b/src/flake8/main/git.py
similarity index 100%
rename from flake8/main/git.py
rename to src/flake8/main/git.py
diff --git a/flake8/main/mercurial.py b/src/flake8/main/mercurial.py
similarity index 100%
rename from flake8/main/mercurial.py
rename to src/flake8/main/mercurial.py
diff --git a/flake8/main/options.py b/src/flake8/main/options.py
similarity index 100%
rename from flake8/main/options.py
rename to src/flake8/main/options.py
diff --git a/flake8/main/setuptools_command.py b/src/flake8/main/setuptools_command.py
similarity index 100%
rename from flake8/main/setuptools_command.py
rename to src/flake8/main/setuptools_command.py
diff --git a/flake8/main/vcs.py b/src/flake8/main/vcs.py
similarity index 100%
rename from flake8/main/vcs.py
rename to src/flake8/main/vcs.py
diff --git a/flake8/options/__init__.py b/src/flake8/options/__init__.py
similarity index 100%
rename from flake8/options/__init__.py
rename to src/flake8/options/__init__.py
diff --git a/flake8/options/aggregator.py b/src/flake8/options/aggregator.py
similarity index 100%
rename from flake8/options/aggregator.py
rename to src/flake8/options/aggregator.py
diff --git a/flake8/options/config.py b/src/flake8/options/config.py
similarity index 100%
rename from flake8/options/config.py
rename to src/flake8/options/config.py
diff --git a/flake8/options/manager.py b/src/flake8/options/manager.py
similarity index 100%
rename from flake8/options/manager.py
rename to src/flake8/options/manager.py
diff --git a/flake8/plugins/__init__.py b/src/flake8/plugins/__init__.py
similarity index 100%
rename from flake8/plugins/__init__.py
rename to src/flake8/plugins/__init__.py
diff --git a/flake8/plugins/_trie.py b/src/flake8/plugins/_trie.py
similarity index 100%
rename from flake8/plugins/_trie.py
rename to src/flake8/plugins/_trie.py
diff --git a/flake8/plugins/manager.py b/src/flake8/plugins/manager.py
similarity index 100%
rename from flake8/plugins/manager.py
rename to src/flake8/plugins/manager.py
diff --git a/flake8/plugins/notifier.py b/src/flake8/plugins/notifier.py
similarity index 100%
rename from flake8/plugins/notifier.py
rename to src/flake8/plugins/notifier.py
diff --git a/flake8/plugins/pyflakes.py b/src/flake8/plugins/pyflakes.py
similarity index 100%
rename from flake8/plugins/pyflakes.py
rename to src/flake8/plugins/pyflakes.py
diff --git a/flake8/processor.py b/src/flake8/processor.py
similarity index 100%
rename from flake8/processor.py
rename to src/flake8/processor.py
diff --git a/flake8/style_guide.py b/src/flake8/style_guide.py
similarity index 100%
rename from flake8/style_guide.py
rename to src/flake8/style_guide.py
diff --git a/flake8/utils.py b/src/flake8/utils.py
similarity index 100%
rename from flake8/utils.py
rename to src/flake8/utils.py
diff --git a/tests/unit/test_utils.py b/tests/unit/test_utils.py
index 062f7f9..5d31e82 100644
--- a/tests/unit/test_utils.py
+++ b/tests/unit/test_utils.py
@@ -71,15 +71,15 @@ def test_fnmatch_returns_the_default_with_empty_default():
 
 def test_filenames_from_a_directory():
     """Verify that filenames_from walks a directory."""
-    filenames = list(utils.filenames_from('flake8/'))
+    filenames = list(utils.filenames_from('src/flake8/'))
     assert len(filenames) > 2
-    assert 'flake8/__init__.py' in filenames
+    assert 'src/flake8/__init__.py' in filenames
 
 
 def test_filenames_from_a_directory_with_a_predicate():
     """Verify that predicates filter filenames_from."""
     filenames = list(utils.filenames_from(
-        arg='flake8/',
+        arg='src/flake8/',
         predicate=lambda filename: filename == 'flake8/__init__.py',
     ))
     assert len(filenames) > 2
diff --git a/tox.ini b/tox.ini
index c17f025..beeb2e3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -24,7 +24,7 @@ deps =
     flake8-docstrings>=0.2.7
     flake8-import-order
 commands =
-    flake8
+    flake8 src/flake8/ tests/ setup.py
 
 [testenv:pylint]
 basepython = python3