diff --git a/.gitmodules b/.gitmodules
index 8defb23..7862383 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,3 +4,6 @@
 [submodule "ext/lwip"]
 	path = ext/lwip
 	url = https://github.com/joseph-henry/lwip.git
+[submodule "ext/lwip-contrib"]
+	path = ext/lwip-contrib
+	url = https://github.com/joseph-henry/lwip-contrib.git
diff --git a/ext/lwip-contrib b/ext/lwip-contrib
new file mode 160000
index 0000000..35b011d
--- /dev/null
+++ b/ext/lwip-contrib
@@ -0,0 +1 @@
+Subproject commit 35b011d4cf4c4b480f8859c456587a884ec9d287