diff --git a/pyproject.toml b/pyproject.toml
index bac2d516..3543c6c2 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -24,7 +24,8 @@ classifiers=[
         "Topic :: Software Development :: Quality Assurance",
 ]
 packages = [
-    { include = "diff_cover" }
+    { include = "diff_cover" },
+    { include = "tests" }
 ]
 include = [
     "templates/*.txt",