diff --git a/MANIFEST.in b/MANIFEST.in
deleted file mode 100644
index 02377d2..0000000
--- a/MANIFEST.in
+++ /dev/null
@@ -1,3 +0,0 @@
-include attrs_strict/py.typed
-recursive-include attrs_strict *.pyi
-recursive-include attrs_strict *.py
diff --git a/pyproject.toml b/pyproject.toml
index 3cac81b..a0f4c3f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,7 +10,7 @@ build-backend = 'setuptools.build_meta'
 line-length = 80
 
 [tool.setuptools_scm]
-write_to = "attrs_strict/_version.py"
+write_to = "src/attrs_strict/_version.py"
 write_to_template = """
 \"\"\" Version information \"\"\"
 
diff --git a/setup.cfg b/setup.cfg
index 0896292..b59e676 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -34,12 +34,21 @@ project_urls =
 [options]
 packages = attrs_strict
 install_requires =
-    attrs
-    typing;python_version<'3.5'
+    attrs>=19.1.0
+    typing>=3.7.4.1;python_version<'3.5'
 python_requires = >=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*, !=3.4.*, !=3.5.*, <4
+package_dir =
+    =src
 tests_require =
     mock;python_version<'3.3'
     pytest >= 4
 
+[options.package_data]
+* = *.pyi
+attrs_strict = py.typed
+
+[options.packages.find]
+where = src
+
 [bdist_wheel]
 universal = true
diff --git a/attrs_strict/__init__.py b/src/attrs_strict/__init__.py
similarity index 100%
rename from attrs_strict/__init__.py
rename to src/attrs_strict/__init__.py
diff --git a/types/__init__.pyi b/src/attrs_strict/__init__.pyi
similarity index 100%
rename from types/__init__.pyi
rename to src/attrs_strict/__init__.pyi
diff --git a/attrs_strict/_commons.py b/src/attrs_strict/_commons.py
similarity index 100%
rename from attrs_strict/_commons.py
rename to src/attrs_strict/_commons.py
diff --git a/types/_commons.pyi b/src/attrs_strict/_commons.pyi
similarity index 100%
rename from types/_commons.pyi
rename to src/attrs_strict/_commons.pyi
diff --git a/attrs_strict/_error.py b/src/attrs_strict/_error.py
similarity index 100%
rename from attrs_strict/_error.py
rename to src/attrs_strict/_error.py
diff --git a/types/_error.pyi b/src/attrs_strict/_error.pyi
similarity index 100%
rename from types/_error.pyi
rename to src/attrs_strict/_error.pyi
diff --git a/attrs_strict/_type_validation.py b/src/attrs_strict/_type_validation.py
similarity index 98%
rename from attrs_strict/_type_validation.py
rename to src/attrs_strict/_type_validation.py
index 98029aa..28026ca 100644
--- a/attrs_strict/_type_validation.py
+++ b/src/attrs_strict/_type_validation.py
@@ -74,9 +74,9 @@ def _validate_elements(attribute, value, expected_type):
     if base_type == typing.Any:
         return
 
-    if base_type != typing.Union and not isinstance(
+    if base_type != typing.Union and not isinstance(  # type: ignore
         value, base_type
-    ):  # type: ignore
+    ):
         raise AttributeTypeError(value, attribute)
 
     if base_type == typing.Union:  # type: ignore
diff --git a/types/_type_validation.pyi b/src/attrs_strict/_type_validation.pyi
similarity index 100%
rename from types/_type_validation.pyi
rename to src/attrs_strict/_type_validation.pyi
diff --git a/src/attrs_strict/_version.pyi b/src/attrs_strict/_version.pyi
new file mode 100644
index 0000000..14a70ab
--- /dev/null
+++ b/src/attrs_strict/_version.pyi
@@ -0,0 +1 @@
+__version__ : str= ...
diff --git a/attrs_strict/py.typed b/src/attrs_strict/py.typed
similarity index 100%
rename from attrs_strict/py.typed
rename to src/attrs_strict/py.typed
diff --git a/tox.ini b/tox.ini
index b182b6f..97be8ea 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,17 +1,16 @@
 [tox]
 envlist =
-        py27,
-        py36,
-        py37,
-        py38,
-        pypy,
-        pypy3,
-        mypy,
-        coverage,
-        merge,
-        fix_lint,
-        docs,
-        package_description,
+    py27,
+    py36,
+    py37,
+    py38,
+    pypy,
+    pypy3,
+    coverage,
+    type,
+    fix_lint,
+    docs,
+    package_description,
 minversion = 3.7
 isolated_build = true
 skip_missing_interpreters = true
@@ -26,45 +25,31 @@ deps =
     pytest-cov
     py{27,py}: mock
     py{27,py}: typing
-
-changedir = tests
-commands = python -m pytest \
+commands = pytest \
            --cov attrs_strict \
            --cov-config "{toxinidir}/tox.ini" \
            --junitxml {toxworkdir}/junit.{envname}.xml \
-           {posargs:.}
-
-
-[testenv:mypy]
-description = check that the type annotations within attrs-strict are self-consistent. Does NOT check if stub files align correctly with actual code.
-basepython = python3.7
-deps = mypy
-setenv =
-    {[testenv]setenv}
-    MYPYPATH={toxinidir}
-commands = mypy types --py2 --strict
-           mypy types --strict
+           {posargs:tests}
 
-[testenv:merge]
+[testenv:type]
 description = try to merge our types against our source
-deps = {[testenv:mypy]deps}
-       retype
-changedir = {envtmpdir}
-commands = python -m retype -p {toxinidir}/types -t {envtmpdir}/attrs_strict {toxinidir}/attrs_strict
-           mypy -p {envtmpdir}/attrs_strict --strict --ignore-missing-imports {posargs}
+deps =
+    mypy == 0.770
+    retype == 19.9.0
+commands =
+    retype -p src/attrs_strict src/attrs_strict -t {envtmpdir}
+    retype -p src/attrs_strict src/attrs_strict/_version.py -t {envtmpdir}
+    mypy {envtmpdir} --strict
 
 [testenv:docs]
 description = invoke sphinx-build to build the HTML docs
-basepython = python3.7
 deps =
-     sphinx
+    sphinx
 commands = sphinx-build -d "{toxworkdir}/docs_doctree" "{toxinidir}/doc" "{toxworkdir}/docs_out" --color -W -bhtml {posargs}
            python -c 'import pathlib; print("documentation available under file://\{0\}".format(pathlib.Path(r"{toxworkdir}") / "docs_out" / "index.html"))'
 
 [testenv:package_description]
-changedir = {toxinidir}
 description = check that the long description is valid
-basepython = python3.7
 deps = twine >= 1.12.1
        readme-renderer[md] >= 24.0
        pep517
@@ -73,7 +58,6 @@ commands = python -m pep517.build -s -b . -o {envtmpdir}
            twine check {envtmpdir}/*
 
 [testenv:pypi_publish]
-changedir = {toxinidir}
 description = Upload a new package to pypi
 deps = twine >= 1.12.1
        pep517
@@ -84,8 +68,6 @@ commands = python -m pep517.build -s -b . -o {envtmpdir}
 
 [testenv:fix_lint]
 description = format the code base to adhere to our styles, and complain about what we cannot do automatically
-basepython = python3.7
-changedir = {toxinidir}
 passenv = {[testenv]passenv}
           # without PROGRAMDATA cloning using git for Windows will fail with an
           # `error setting certificate verify locations` error
@@ -126,9 +108,12 @@ exclude_lines =
     ^if __name__ == ['"]__main__['"]:$
 
 [coverage:paths]
-source = attrs_strict
+source = src/attrs_strict
          */.tox/*/lib/python*/site-packages/attrs_strict
          */.tox/pypy*/site-packages/attrs_strict
          */.tox\*\Lib\site-packages\attrs_strict
          */attrs_strict
          *\attrs_strict
+
+[pytest]
+junit_family=xunit1