diff --git a/libs/surfaces/generic_midi/interface.cc b/libs/surfaces/generic_midi/interface.cc
index b7e7b63dd7..04254cb974 100644
--- a/libs/surfaces/generic_midi/interface.cc
+++ b/libs/surfaces/generic_midi/interface.cc
@@ -65,7 +65,11 @@ static ControlProtocolDescriptor generic_midi_descriptor = {
 	/*supports_feedback : */   true,
 	/*probe :             */   probe_generic_midi_protocol,
 	/*initialize :        */   new_generic_midi_protocol,
-	/*destroy :           */   delete_generic_midi_protocol
+	/*destroy :           */   delete_generic_midi_protocol,
+	/*request_buffer_factory : */ 0  /* no buffer factory because this runs
+	                                  * in the midiUI event loop (which has
+	                                  * its own request buffer factory.
+	                                  */
 };
 
 extern "C" ARDOURSURFACE_API ControlProtocolDescriptor* protocol_descriptor () { return &generic_midi_descriptor; }