diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..cc4f798
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "third_party/cleantest"]
+	path = third_party/cleantest
+	url = https://github.com/clean-test/clean-test
diff --git a/third_party/cleantest b/third_party/cleantest
new file mode 160000
index 0000000..552af39
--- /dev/null
+++ b/third_party/cleantest
@@ -0,0 +1 @@
+Subproject commit 552af39254168c8f0efdfb740c33c0f32392743b