diff --git a/libs/ardour/ladspa_plugin.cc b/libs/ardour/ladspa_plugin.cc
index 9289899f51..6a27b8571a 100644
--- a/libs/ardour/ladspa_plugin.cc
+++ b/libs/ardour/ladspa_plugin.cc
@@ -523,14 +523,14 @@ LadspaPlugin::connect_and_run (vector<Sample*>& bufs, uint32_t nbufs, int32_t& i
 	while (port_index < parameter_count()) {
 		if (LADSPA_IS_PORT_AUDIO (port_descriptor(port_index))) {
 			if (LADSPA_IS_PORT_INPUT (port_descriptor(port_index))) {
-				connect_port (port_index, bufs[min((uint32_t) in_index,nbufs - 1)]);
+				connect_port (port_index, bufs[min((uint32_t) in_index,nbufs - 1)] + offset);
 				//cerr << this << ' ' << name() << " @ " << offset << " inport " << in_index << " = buf " 
 				//     << min((uint32_t)in_index,nbufs) << " = " << &bufs[min((uint32_t)in_index,nbufs)][offset] << endl;
 				in_index++;
 
 
 			} else if (LADSPA_IS_PORT_OUTPUT (port_descriptor (port_index))) {
-				connect_port (port_index, bufs[min((uint32_t) out_index,nbufs - 1)]);
+				connect_port (port_index, bufs[min((uint32_t) out_index,nbufs - 1)] + offset);
 				// cerr << this << ' ' << name() << " @ " << offset << " outport " << out_index << " = buf " 
 				//     << min((uint32_t)out_index,nbufs) << " = " << &bufs[min((uint32_t)out_index,nbufs)][offset] << endl;
 				out_index++;
diff --git a/libs/ardour/lv2_plugin.cc b/libs/ardour/lv2_plugin.cc
index 32160abb58..10648c36d3 100644
--- a/libs/ardour/lv2_plugin.cc
+++ b/libs/ardour/lv2_plugin.cc
@@ -425,11 +425,11 @@ LV2Plugin::connect_and_run (vector<Sample*>& bufs, uint32_t nbufs, int32_t& in_i
 		if (parameter_is_audio(port_index)) {
 			if (parameter_is_input(port_index)) {
 				slv2_instance_connect_port(_instance, port_index,
-						bufs[min((uint32_t)in_index, nbufs - 1)]);
+							   bufs[min((uint32_t)in_index, nbufs - 1)] + offset);
 				in_index++;
 			} else if (parameter_is_output(port_index)) {
 				slv2_instance_connect_port(_instance, port_index,
-						bufs[min((uint32_t)out_index, nbufs - 1)]);
+							   bufs[min((uint32_t)out_index, nbufs - 1)] + offset);
 				out_index++;
 			}
 		}