diff --git a/src/lsdb.hpp b/src/lsdb.hpp
index ef45cea..c5dcbed 100644
--- a/src/lsdb.hpp
+++ b/src/lsdb.hpp
@@ -239,6 +239,7 @@
   seconds m_lsaRefreshTime;
   std::string m_thisRouterPrefix;
 
+  static const ndn::time::seconds GRACE_PERIOD;
 };
 
 }//namespace nlsr