diff --git a/.gitmodules b/.gitmodules
index 19f0e34..8defb23 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,3 +1,6 @@
 [submodule "ext/ZeroTierOne"]
 	path = ext/ZeroTierOne
 	url = https://github.com/zerotier/ZeroTierOne.git
+[submodule "ext/lwip"]
+	path = ext/lwip
+	url = https://github.com/joseph-henry/lwip.git
diff --git a/ext/lwip b/ext/lwip
new file mode 160000
index 0000000..b3a9394
--- /dev/null
+++ b/ext/lwip
@@ -0,0 +1 @@
+Subproject commit b3a939417e936a933ba287aee79eff8662198cad