diff --git a/src/branch2.hpp b/src/branch2.hpp
index 0afcd05e..6965f6a9 100644
--- a/src/branch2.hpp
+++ b/src/branch2.hpp
@@ -1,3 +1,5 @@
+#pragma once
+
 #include "ghc/filesystem.hpp"
 #include "toml.hpp"