diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..bff9634
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "arena.h"]
+	path = arena.h
+	url = ssh://gitea@188.157.159.51:8122/prenex/arena.h.git
diff --git a/arena.h b/arena.h
new file mode 160000
index 0000000..70f97b8
--- /dev/null
+++ b/arena.h
@@ -0,0 +1 @@
+Subproject commit 70f97b8291454efbf9606051352c15ea6ebca319