diff --git a/libraries/chain/db_init.cpp b/libraries/chain/db_init.cpp
index 72841afe..956e34a7 100644
--- a/libraries/chain/db_init.cpp
+++ b/libraries/chain/db_init.cpp
@@ -247,6 +247,7 @@ void database::initialize_evaluators()
    register_evaluator<create_son_evaluator>();
    register_evaluator<update_son_evaluator>();
    register_evaluator<delete_son_evaluator>();
+   register_evaluator<son_heartbeat_evaluator>();
 }
 
 void database::initialize_indexes()
diff --git a/libraries/chain/include/graphene/chain/son_object.hpp b/libraries/chain/include/graphene/chain/son_object.hpp
index 5db51ac0..4cbff5ed 100644
--- a/libraries/chain/include/graphene/chain/son_object.hpp
+++ b/libraries/chain/include/graphene/chain/son_object.hpp
@@ -92,7 +92,7 @@ namespace graphene { namespace chain {
    using son_stats_index = generic_index<son_statistics_object, son_stats_multi_index_type>;
 } } // graphene::chain
 
-FC_REFLECT_ENUM(graphene::chain::son_status, (inactive)(active)(in_maintenance) )
+FC_REFLECT_ENUM(graphene::chain::son_status, (inactive)(active)(in_maintenance)(deregistered) )
 
 FC_REFLECT_DERIVED( graphene::chain::son_object, (graphene::db::object),
                     (son_account)(vote_id)(total_votes)(url)(deposit)(signing_key)(pay_vb) )
diff --git a/tests/tests/son_operations_tests.cpp b/tests/tests/son_operations_tests.cpp
index a458b45e..3740335c 100644
--- a/tests/tests/son_operations_tests.cpp
+++ b/tests/tests/son_operations_tests.cpp
@@ -652,4 +652,88 @@ BOOST_AUTO_TEST_CASE( son_witness_proposal_test )
       generate_block();
    } FC_LOG_AND_RETHROW()
 
+} 
+
+BOOST_AUTO_TEST_CASE( son_heartbeat_test ) {
+
+   try
+   {
+      INVOKE(create_son_test);
+      GET_ACTOR(alice);
+
+      {
+         // Send Heartbeat for an inactive SON
+         son_heartbeat_operation op;
+         op.owner_account = alice_id;
+         op.son_id = son_id_type(0);
+         op.ts = fc::time_point::now();
+
+         trx.operations.push_back(op);
+         sign(trx, alice_private_key);
+         // Expect an exception
+         GRAPHENE_REQUIRE_THROW(PUSH_TX( db, trx, ~0), fc::exception);
+         trx.clear();
+      }
+      generate_block();
+
+      const auto& idx = db.get_index_type<son_index>().indices().get<by_account>();
+      BOOST_REQUIRE( idx.size() == 1 );
+      auto obj = idx.find( alice_id );
+      BOOST_REQUIRE( obj != idx.end() );
+
+      const auto& sidx = db.get_index_type<son_stats_index>().indices().get<by_id>();
+      BOOST_REQUIRE( sidx.size() == 1 );
+      auto son_stats_obj = sidx.find( obj->statistics );
+      BOOST_REQUIRE( son_stats_obj != sidx.end() );
+
+      // Modify SON's status to in_maintenance
+      db.modify( *obj, [&]( son_object& _s)
+      {
+         _s.status = son_status::in_maintenance;
+      });
+
+      db.modify( *son_stats_obj, [&]( son_statistics_object& _s)
+      {
+         _s.last_down_timestamp = fc::time_point_sec(db.head_block_time() - fc::hours(1));
+      });
+
+      uint64_t downtime = 0;
+
+      {
+         generate_block();
+         // Send Heartbeat for an in_maintenance SON
+         son_heartbeat_operation op;
+         op.owner_account = alice_id;
+         op.son_id = son_id_type(0);
+         op.ts = (db.head_block_time()+fc::seconds(2*db.block_interval()));
+
+         trx.operations.push_back(op);
+         sign(trx, alice_private_key);
+         PUSH_TX( db, trx, ~0);
+         generate_block();
+         trx.clear();
+         BOOST_REQUIRE_EQUAL(son_stats_obj->current_interval_downtime, op.ts.sec_since_epoch() - son_stats_obj->last_down_timestamp.sec_since_epoch());
+         downtime = op.ts.sec_since_epoch() - son_stats_obj->last_down_timestamp.sec_since_epoch();
+         BOOST_CHECK( obj->status == son_status::active);
+         BOOST_CHECK( son_stats_obj->last_active_timestamp == op.ts);
+      }
+
+      {
+         generate_block();
+         // Send Heartbeat for an active SON
+         son_heartbeat_operation op;
+         op.owner_account = alice_id;
+         op.son_id = son_id_type(0);
+         op.ts = (db.head_block_time()+fc::seconds(2*db.block_interval()));
+
+         trx.operations.push_back(op);
+         sign(trx, alice_private_key);
+         PUSH_TX( db, trx, ~0);
+         generate_block();
+         trx.clear();
+         BOOST_REQUIRE_EQUAL(son_stats_obj->current_interval_downtime, downtime);
+         BOOST_CHECK( obj->status == son_status::active);
+         BOOST_CHECK( son_stats_obj->last_active_timestamp == op.ts);
+      }
+   } FC_LOG_AND_RETHROW()
 } BOOST_AUTO_TEST_SUITE_END()