diff --git a/pyproject.toml b/pyproject.toml
index fcaebb0..6fa3795 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -39,6 +39,18 @@ build-backend = "hatchling.build"
 [tool.hatch.build.targets.wheel]
 packages = ["src/wikiq"]
 
+# Without an explicit list hatchling walks the whole working tree, which sweeps
+# in any local virtualenv and editor state while still omitting the test dumps,
+# since those are gitignored. Tests run from a clone of the repository rather
+# than from the sdist.
+[tool.hatch.build.targets.sdist]
+include = [
+    "src/wikiq",
+    "README.md",
+    "COPYING",
+    "pyproject.toml",
+]
+
 [dependency-groups]
 dev = [
     "ipython>=8.18.1",