diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..ad3f0c8
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "third_party/make-env"]
+	path = third_party/make-env
+	url = https://github.com/SymbiFlow/make-env.git
diff --git a/third_party/make-env b/third_party/make-env
new file mode 160000
index 0000000..59adb0f
--- /dev/null
+++ b/third_party/make-env
@@ -0,0 +1 @@
+Subproject commit 59adb0f248cc4a5d764b6b06224bf6adea7fa36e