diff --git a/src/policy_cache.hpp b/src/policy_cache.hpp
index c1102113..3fee4f12 100644
--- a/src/policy_cache.hpp
+++ b/src/policy_cache.hpp
@@ -79,5 +79,5 @@ public:
 
 private:
   unsigned _max_size;
-  boost::unordered_flat_map<std::string,std::string> _cache;
+  Map      _cache;
 };