diff --git a/src/branches2.hpp b/src/branches2.hpp
index e95f10ed..243ce16c 100644
--- a/src/branches2.hpp
+++ b/src/branches2.hpp
@@ -12,4 +12,7 @@ class Branches2 : public std::vector<Branch2Vec>
 {
 public:
   uint64_t min_free_space;
+
+private:
+  std::vector<Branch2Vec> _branches;
 };