diff --git a/libraries/chain/son_evaluator.cpp b/libraries/chain/son_evaluator.cpp
index 619d2e22..fc4802d2 100644
--- a/libraries/chain/son_evaluator.cpp
+++ b/libraries/chain/son_evaluator.cpp
@@ -123,6 +123,22 @@ object_id_type son_heartbeat_evaluator::do_apply(const son_heartbeat_operation&
     auto itr = idx.find(op.son_id);
     if(itr != idx.end())
     {
+        const global_property_object& gpo = db().get_global_properties();
+        vector<son_id_type> active_son_ids;
+        active_son_ids.reserve(gpo.active_sons.size());
+        std::transform(gpo.active_sons.begin(), gpo.active_sons.end(),
+                        std::inserter(active_son_ids, active_son_ids.end()),
+                        [](const son_info& swi) {
+            return swi.son_id;
+        });
+
+        auto it_son = std::find(active_son_ids.begin(), active_son_ids.end(), op.son_id);
+        bool is_son_active = true;
+
+        if(it_son == active_son_ids.end()) {
+            is_son_active = false;
+        }
+
         if(itr->status == son_status::in_maintenance) {
             db().modify( itr->statistics( db() ), [&]( son_statistics_object& sso )
             {
@@ -130,8 +146,12 @@ object_id_type son_heartbeat_evaluator::do_apply(const son_heartbeat_operation&
                 sso.last_active_timestamp = op.ts;
             } );
 
-            db().modify(*itr, [&op](son_object &so) {
-                so.status = son_status::active;
+            db().modify(*itr, [&is_son_active](son_object &so) {
+                if(is_son_active) {
+                    so.status = son_status::active;
+                } else {
+                    so.status = son_status::inactive;
+                }
             });
         } else if (itr->status == son_status::active) {
             db().modify( itr->statistics( db() ), [&]( son_statistics_object& sso )
diff --git a/libraries/plugins/peerplays_sidechain/peerplays_sidechain_plugin.cpp b/libraries/plugins/peerplays_sidechain/peerplays_sidechain_plugin.cpp
index e78c78c5..2874605b 100644
--- a/libraries/plugins/peerplays_sidechain/peerplays_sidechain_plugin.cpp
+++ b/libraries/plugins/peerplays_sidechain/peerplays_sidechain_plugin.cpp
@@ -186,6 +186,10 @@ void peerplays_sidechain_plugin_impl::heartbeat_loop()
 {
    chain::database& d = plugin.database();
    chain::son_id_type son_id = *(_sons.begin());
+   const auto& idx = d.get_index_type<chain::son_index>().indices().get<by_id>();
+   auto son_obj = idx.find( son_id );
+   if(son_obj == idx.end())
+      return;
    const chain::global_property_object& gpo = d.get_global_properties();
    vector<son_id_type> active_son_ids;
    active_son_ids.reserve(gpo.active_sons.size());
@@ -196,11 +200,9 @@ void peerplays_sidechain_plugin_impl::heartbeat_loop()
    });
 
    auto it = std::find(active_son_ids.begin(), active_son_ids.end(), son_id);
-   if(it != active_son_ids.end()) {
+   if(it != active_son_ids.end() || son_obj->status == chain::son_status::in_maintenance) {
       ilog("peerplays_sidechain_plugin:  sending heartbeat");
       chain::son_heartbeat_operation op;
-      const auto& idx = d.get_index_type<chain::son_index>().indices().get<by_id>();
-      auto son_obj = idx.find( son_id );
       op.owner_account = son_obj->son_account;
       op.son_id = son_id;
       op.ts = fc::time_point::now() + fc::seconds(0);
diff --git a/tests/tests/son_operations_tests.cpp b/tests/tests/son_operations_tests.cpp
index ad8cf0bd..f6037084 100644
--- a/tests/tests/son_operations_tests.cpp
+++ b/tests/tests/son_operations_tests.cpp
@@ -723,7 +723,40 @@ BOOST_AUTO_TEST_CASE( son_heartbeat_test ) {
          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();
+         downtime += op.ts.sec_since_epoch() - son_stats_obj->last_down_timestamp.sec_since_epoch();
+         BOOST_CHECK( obj->status == son_status::inactive);
+         BOOST_CHECK( son_stats_obj->last_active_timestamp == op.ts);
+      }
+
+      // Modify SON's status to in_maintenance
+      db.modify( *obj, [&]( son_object& _s)
+      {
+         _s.status = son_status::in_maintenance;
+      });
+
+      // SON is selected as one of the active SONs
+      db.modify( db.get_global_properties(), [&]( global_property_object& _gpo )
+      {
+         son_info son_inf;
+         son_inf.son_id = son_id_type(0);
+         _gpo.active_sons.push_back(son_inf);
+      });
+
+      {
+         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, 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);
       }