diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 000000000..dd8841835
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "protocol"]
+	path = protocol
+	url = https://github.com/sok-im/protocol
diff --git a/protocol b/protocol
new file mode 160000
index 000000000..91e8d26ed
--- /dev/null
+++ b/protocol
@@ -0,0 +1 @@
+Subproject commit 91e8d26ed5b8ebd2711483bb558e797fa40f4612