diff --git a/pyproject.toml b/pyproject.toml
index e48ec5e..ee3ee87 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -5,7 +5,10 @@ license = "MIT"
 authors = ["Ethan Paul <24588726+enpaul@users.noreply.github.com>"]
 description = "Tox plugin to install Tox environment dependencies using the Poetry backend and lockfile"
 repository = "https://github.com/enpaul/tox-poetry-installer/"
-packages = [{include = "tox_poetry_installer.py"}]
+packages = [
+  {include = "tox_poetry_installer.py"},
+  {include = "tests/*.py", format = "sdist"}
+]
 keywords = ["tox", "poetry", "plugin"]
 readme = "README.md"
 classifiers = [