diff --git a/src/rose/rose_build_bytecode.cpp b/src/rose/rose_build_bytecode.cpp
index 5c56f2d5..b0c251f4 100644
--- a/src/rose/rose_build_bytecode.cpp
+++ b/src/rose/rose_build_bytecode.cpp
@@ -249,9 +249,6 @@ public:
 };
 
 struct build_context : boost::noncopyable {
-    /** \brief minimum depth in number of hops from root/anchored root. */
-    map<RoseVertex, u32> depths;
-
     /** \brief information about engines to the left of a vertex */
     map<RoseVertex, left_build_info> leftfix_info;