diff --git a/pyproject.toml b/pyproject.toml
index 3c1fac4..2b6de52 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -31,6 +31,8 @@ packages = [
 include = [
     "utcnow/*.py",
     "utcnow/*.pyi",
+    "utcnow/protobuf/*.py",
+    "utcnow/protobuf/*.pyi",
     "utcnow/py.typed",
 ]