diff --git a/src/branches2.hpp b/src/branches2.hpp
index d12a6c35..d1e220f3 100644
--- a/src/branches2.hpp
+++ b/src/branches2.hpp
@@ -1,3 +1,5 @@
+#pragma once
+
 #include "branch2.hpp"
 #include "branch_tier.hpp"