diff --git a/.mypy.ini b/.mypy.ini
index 07fe9d7..a396b02 100644
--- a/.mypy.ini
+++ b/.mypy.ini
@@ -5,7 +5,7 @@ error_summary = true
 files =
   packaging/,
   tests/,
-  propcache/
+  src/propcache/
 
 # check_untyped_defs = true
 
diff --git a/Makefile b/Makefile
index 27e2121..a2d5360 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-PYXS = $(wildcard propcache/*.pyx)
+PYXS = $(wildcard src/propcache/*.pyx)
 SRC = propcache tests
 
 all: test
@@ -15,8 +15,8 @@ all: test
 	touch .install-cython
 
 
-propcache/%.c: propcache/%.pyx
-	python -m cython -3 -o $@ $< -I propcache
+src/propcache/%.c: src/propcache/%.pyx
+	python -m cython -3 -o $@ $< -I src/propcache
 
 
 .cythonize: .install-cython $(PYXS:.pyx=.c)
@@ -25,7 +25,7 @@ propcache/%.c: propcache/%.pyx
 cythonize: .cythonize
 
 
-.develop: .install-deps $(shell find propcache -type f)
+.develop: .install-deps $(shell find src/propcache -type f)
 	@pip install -e .
 	@touch .develop
 
@@ -39,15 +39,15 @@ endif
 lint: fmt
 
 test: lint .develop
-	pytest ./tests ./propcache
+	pytest ./tests ./src/propcache
 
 
 vtest: lint .develop
-	pytest ./tests ./propcache -v
+	pytest ./tests ./src/propcache -v
 
 
 cov: lint .develop
-	pytest --cov propcache --cov-report html --cov-report term ./tests/ ./propcache/
+	pytest --cov src/propcache --cov-report html --cov-report term ./tests/ ./src/propcache/
 	@echo "open file://`pwd`/htmlcov/index.html"
 
 
diff --git a/docs/conf.py b/docs/conf.py
index 841b42a..7e007ce 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -40,8 +40,7 @@
 
 
 _docs_path = Path(__file__).parent
-_version_path = _docs_path / "../propcache/__init__.py"
-
+_version_path = _docs_path / "../src/propcache/__init__.py"
 
 with _version_path.open() as fp:
     try:
diff --git a/pyproject.toml b/pyproject.toml
index a1ba466..b09b2ad 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -12,7 +12,7 @@ build-backend = "pep517_backend.hooks"  # wraps `setuptools.build_meta`
 
 [tool.local.cythonize]
 # This attr can contain multiple globs
-src = ["propcache/*.pyx"]
+src = ["src/propcache/*.pyx"]
 
 [tool.local.cythonize.env]
 # Env vars provisioned during cythonize call
diff --git a/pytest.ini b/pytest.ini
index dc242af..4473470 100644
--- a/pytest.ini
+++ b/pytest.ini
@@ -85,4 +85,6 @@ norecursedirs =
 
 testpaths = tests/
 
+pythonpath = src
+
 xfail_strict = true
diff --git a/setup.cfg b/setup.cfg
index acc06dc..85295f6 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -57,10 +57,11 @@ python_requires = >=3.8
 # Ref:
 # https://setuptools.pypa.io/en/latest/userguide/declarative_config.html#using-a-src-layout
 # (`src/` layout)
-# package_dir =
-#   = src
+package_dir =
+    =src
 packages =
   propcache
+
 # https://setuptools.pypa.io/en/latest/deprecated/zip_safe.html
 zip_safe = False
 include_package_data = True
diff --git a/propcache/__init__.py b/src/propcache/__init__.py
similarity index 100%
rename from propcache/__init__.py
rename to src/propcache/__init__.py
diff --git a/propcache/_helpers.py b/src/propcache/_helpers.py
similarity index 100%
rename from propcache/_helpers.py
rename to src/propcache/_helpers.py
diff --git a/propcache/_helpers_c.pyx b/src/propcache/_helpers_c.pyx
similarity index 100%
rename from propcache/_helpers_c.pyx
rename to src/propcache/_helpers_c.pyx
diff --git a/propcache/_helpers_py.py b/src/propcache/_helpers_py.py
similarity index 100%
rename from propcache/_helpers_py.py
rename to src/propcache/_helpers_py.py
diff --git a/propcache/api.py b/src/propcache/api.py
similarity index 100%
rename from propcache/api.py
rename to src/propcache/api.py
diff --git a/propcache/py.typed b/src/propcache/py.typed
similarity index 100%
rename from propcache/py.typed
rename to src/propcache/py.typed