diff --git a/.gitmodules b/.gitmodules
index 338f571e..17f593df 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -73,3 +73,6 @@
 [submodule "plugins/gratitude"]
 	path = plugins/gratitude
 	url = https://github.com/BlythT/Gratitude-Millennium-Plugin
+[submodule "plugins/csst-at-extension"]
+	path = plugins/csst-at-extension
+	url = https://github.com/TOR968/csst-at-extension
diff --git a/plugins/csst-at-extension b/plugins/csst-at-extension
new file mode 160000
index 00000000..e080c75c
--- /dev/null
+++ b/plugins/csst-at-extension
@@ -0,0 +1 @@
+Subproject commit e080c75cb7b8ec17f1f14b81c86649a132de0a41