diff --git a/.gitmodules b/.gitmodules
index 389fb200..33d73599 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -236,3 +236,9 @@
 [submodule "mods/mob_horse"]
 	path = mods/mob_horse
 	url = https://git.tchncs.de/Illuna-Minetest/mob_horse
+[submodule "mods/matrix"]
+	path = mods/matrix
+	url = https://github.com/entuland/lua-matrix
+[submodule "mods/rhotator"]
+	path = mods/rhotator
+	url = https://git.tchncs.de/Illuna-Minetest/rhotator
diff --git a/mods/matrix b/mods/matrix
new file mode 160000
index 00000000..b7322ea3
--- /dev/null
+++ b/mods/matrix
@@ -0,0 +1 @@
+Subproject commit b7322ea304ecf05f4dff9f230a3930168c204037
diff --git a/mods/rhotator b/mods/rhotator
new file mode 160000
index 00000000..55fc4208
--- /dev/null
+++ b/mods/rhotator
@@ -0,0 +1 @@
+Subproject commit 55fc42085da9eaae06c76a5cb10bfc4872f808be