diff --git a/.gitmodules b/.gitmodules
index 0dcbfef..c13cdb4 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -15,3 +15,6 @@
 [submodule "source/vtr-verilog-to-routing"]
 	path = source/vtr-verilog-to-routing
 	url = ../vtr-verilog-to-routing
+[submodule "third_party/make-env"]
+	path = third_party/make-env
+	url = https://github.com/SymbiFlow/make-env/
diff --git a/third_party/make-env b/third_party/make-env
new file mode 160000
index 0000000..0696632
--- /dev/null
+++ b/third_party/make-env
@@ -0,0 +1 @@
+Subproject commit 069663287b59b07e67c15fc88ec9faf850ca1580