diff --git a/src/branch_tier.hpp b/src/branch_tier.hpp
index bbf680bd..7d5b5abd 100644
--- a/src/branch_tier.hpp
+++ b/src/branch_tier.hpp
@@ -12,6 +12,9 @@ public:
   BranchTier();
   BranchTier(toml::value const &);
 
+public:
+  void copy_enabled_rw(BranchTier&);
+
 public:
   uint64_t min_free_space;