diff --git a/gtk2_ardour/midi_channel_selector.cc b/gtk2_ardour/midi_channel_selector.cc
index 40ab968358..d76a5d5ff2 100644
--- a/gtk2_ardour/midi_channel_selector.cc
+++ b/gtk2_ardour/midi_channel_selector.cc
@@ -650,6 +650,8 @@ MidiChannelSelectorWindow::playback_mode_changed ()
 		}
 	}
 
+	playback_mask_changed(); // update buttons
+
 	last_drawn_playback_mode = mode;
 }
 
@@ -748,6 +750,8 @@ MidiChannelSelectorWindow::capture_mode_changed ()
 		}
 	}
 
+	capture_mask_changed (); // udpate buttons
+
 	last_drawn_capture_mode = mode;
 }