diff --git a/.gitmodules b/.gitmodules
index d543125..2ce3a07 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -4,3 +4,6 @@
 [submodule "apps/frontend/src"]
 	path = apps/frontend/src
 	url = https://gitea.mindboost.team/Mindboost/mindboost-webapp.git
+[submodule "apps/tools/invoiceninja/dockerfiles"]
+	path = apps/tools/invoiceninja/dockerfiles
+	url = https://github.com/invoiceninja/dockerfiles.git