diff --git a/README.md b/README.md
index 5ee5391..e0500bd 100644
--- a/README.md
+++ b/README.md
@@ -22,6 +22,7 @@ A GlobalProtect VPN client (GUI) for Linux based on Openconnect and built with Q
 ```sh
 git clone https://github.com/yuezk/GlobalProtect-openconnect.git
 cd GlobalProtect-openconnect
+git submodule init && git submodule update
 qmake CONFIG+=release
 make
 sudo make install