Index: libs/ardour/session_process.cc
===================================================================
--- libs/ardour/session_process.cc	(revision 3794)
+++ libs/ardour/session_process.cc	(working copy)
@@ -47,6 +47,9 @@
 {
 	_silent = false;
 
+	if( !_exporting && synced_to_jack() && _slave ) {
+	    follow_slave(nframes,0);
+	}
 	if (synced_to_jack() && waiting_to_start) {
 		if ( _engine.transport_state() == AudioEngine::TransportRolling) {
 			actually_start_transport ();
@@ -301,9 +304,11 @@
 		}
 		
 		if (!_exporting && _slave) {
+		    if( !synced_to_jack() ) {
 			if (!follow_slave (nframes, 0)) {
 				return;
 			}
+		    }
 		} 
 
 		if (_transport_speed == 0) {
@@ -733,9 +738,11 @@
 	}
 
 	if (!_exporting && _slave) {
+	    if( !synced_to_jack() ) {
 		if (!follow_slave (nframes, 0)) {
 			return;
 		}
+	    }
 	} 
 
 	if (_transport_speed == 0) {