diff --git a/gtk2_ardour/midi_streamview.cc b/gtk2_ardour/midi_streamview.cc
index ed60b14256..56e34c8a79 100644
--- a/gtk2_ardour/midi_streamview.cc
+++ b/gtk2_ardour/midi_streamview.cc
@@ -628,3 +628,17 @@ MidiStreamView::update_rec_box ()
 	mrv->extend_active_notes ();
 }
 
+uint8_t
+MidiStreamView::y_to_note (double y) const
+{
+	int const n = ((contents_height() - y - 1) / contents_height() * (double)contents_note_range())
+		+ lowest_note();
+
+	if (n < 0) {
+		return 0;
+	} else if (n > 127) {
+		return 127;
+	}
+	
+	return n;
+}
diff --git a/gtk2_ardour/midi_streamview.h b/gtk2_ardour/midi_streamview.h
index 0774fd61bd..a939d8ea7d 100644
--- a/gtk2_ardour/midi_streamview.h
+++ b/gtk2_ardour/midi_streamview.h
@@ -83,10 +83,7 @@ class MidiStreamView : public StreamView
 		{ return contents_height()
 			- (note + 1 - lowest_note()) * note_height() + 1; }
 
-	inline uint8_t y_to_note(double y) const
-		{ return (uint8_t)((contents_height() - y - 1)
-				/ contents_height() * (double)contents_note_range())
-				+ lowest_note(); }
+	uint8_t y_to_note(double y) const;
 
 	inline double note_height() const
 		{ return contents_height() / (double)contents_note_range(); }