diff --git a/src/branches2.hpp b/src/branches2.hpp
index d50aa051..e164e8b1 100644
--- a/src/branches2.hpp
+++ b/src/branches2.hpp
@@ -7,5 +7,5 @@ typedef std::vector<Branch2> Branch2Vec;
 
 class Branches2 : public std::vector<Branch2Vec>
 {
-  
+  uint64_t min_free_space;
 };