diff --git a/libs/ardour/ardour/vst3_plugin.h b/libs/ardour/ardour/vst3_plugin.h
index 4819453227..0591df8dfd 100644
--- a/libs/ardour/ardour/vst3_plugin.h
+++ b/libs/ardour/ardour/vst3_plugin.h
@@ -143,10 +143,11 @@ public:
 	uint32_t n_audio_aux_out () const { return _n_aux_outputs; }
 
 	struct AudioBusInfo {
-		AudioBusInfo (Vst::BusType t, int32_t c) : type (t), n_chn (c) {}
+		AudioBusInfo (Vst::BusType t, int32_t c, bool a) : type (t), n_chn (c), dflt (a) {}
 		AudioBusInfo () : type (Vst::kMain), n_chn (0) {}
 		Vst::BusType type;
 		int32_t      n_chn;
+		bool         dflt; // kDefaultActive
 	};
 
 	std::map<int, AudioBusInfo> const& bus_info_in () const { return _bus_info_in; }
diff --git a/libs/ardour/vst3_plugin.cc b/libs/ardour/vst3_plugin.cc
index b9181af7e6..686102d886 100644
--- a/libs/ardour/vst3_plugin.cc
+++ b/libs/ardour/vst3_plugin.cc
@@ -96,13 +96,19 @@ VST3Plugin::init ()
 	_plug->OnResizeView.connect_same_thread (_connections, boost::bind (&VST3Plugin::forward_resize_view, this, _1, _2));
 	_plug->OnParameterChange.connect_same_thread (_connections, boost::bind (&VST3Plugin::parameter_change_handler, this, _1, _2, _3));
 
-	/* assume all I/O is connected by default */
-	for (int32_t i = 0; i < (int32_t)_plug->n_audio_inputs (); ++i) {
-		_connected_inputs.push_back (true);
+	/* assume only default active busses are connected */
+	for (auto const& abi : _plug->bus_info_in ()) {
+		for (int32_t i = 0; i < abi.second.n_chn; ++i) {
+		_connected_inputs.push_back (abi.second.dflt);
+		}
 	}
-	for (int32_t i = 0; i < (int32_t)_plug->n_audio_outputs (); ++i) {
-		_connected_outputs.push_back (true);
+
+	for (auto const& abi : _plug->bus_info_out ()) {
+		for (int32_t i = 0; i < abi.second.n_chn; ++i) {
+		_connected_outputs.push_back (abi.second.dflt);
+		}
 	}
+
 	/* pre-configure from GUI thread */
 	_plug->enable_io (_connected_inputs, _connected_outputs);
 }
@@ -1747,9 +1753,9 @@ VST3PI::count_channels (Vst::MediaType media, Vst::BusDirection dir, Vst::BusTyp
 				n_channels += bus.channelCount;
 
 				if (dir == Vst::kInput) {
-					_bus_info_in.insert (std::make_pair(i, AudioBusInfo (type, bus.channelCount)));
+					_bus_info_in.insert (std::make_pair(i, AudioBusInfo (type, bus.channelCount, bus.flags & Vst::BusInfo::kDefaultActive)));
 				} else {
-					_bus_info_out.insert (std::make_pair(i, AudioBusInfo (type, bus.channelCount)));
+					_bus_info_out.insert (std::make_pair(i, AudioBusInfo (type, bus.channelCount, bus.flags & Vst::BusInfo::kDefaultActive)));
 				}
 			}
 		}