diff --git a/pyproject.toml b/pyproject.toml
index 91d174f..6dce854 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -8,6 +8,13 @@ dependencies = [
     "gatelock @ git+https://github.com/kuhyx/gatelock@v0.1.0",
 ]
 
+[tool.setuptools.packages.find]
+# This repo also holds stronglift_replacement/ (an unrelated Flutter app, not
+# a Python package); without this, setuptools' automatic flat-layout
+# discovery sees two top-level directories and refuses to guess which is the
+# installable package.
+include = ["screen_locker*"]
+
 [tool.ruff]
 target-version = "py310"
 include = ["*.py", "**/*.py"]