diff --git a/pyproject.toml b/pyproject.toml
index 5082f47..c38756a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -43,3 +43,4 @@ dynamic = ["version"]
 
 [tool.flit.sdist]
 exclude = [".gitignore", ".github/"]
+include = ["tests"]