diff --git a/src/policy_cache.hpp b/src/policy_cache.hpp
index b5db5c15..e65b9315 100644
--- a/src/policy_cache.hpp
+++ b/src/policy_cache.hpp
@@ -38,7 +38,7 @@ class PolicyCache
 {
 public:
   typedef uint64_t Key;
-  typedef boost::flyweight<std::string> Val;
+  typedef boost::flyweight<std::string,boost::flyweights::no_tracking> Val;
   typedef boost::concurrent_flat_map<Key,Val> Map;
 
 public: