diff --git a/.gitmodules b/.gitmodules
index 19dd6b3..b4f2123 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -451,3 +451,6 @@
 [submodule "fakelib"]
 	path = fakelib
 	url = https://sys4.fr/gitea/mtcontrib/fakelib.git
+[submodule "lighting_monoids"]
+	path = lighting_monoids
+	url = https://sys4.fr/gitea/mtcontrib/lighting_monoids.git
diff --git a/lighting_monoids b/lighting_monoids
new file mode 160000
index 0000000..7ac833b
--- /dev/null
+++ b/lighting_monoids
@@ -0,0 +1 @@
+Subproject commit 7ac833bb19127921fa9a8c6805b954a3581815a9