diff --git a/omnivore8bit/hex_edit/hex_editor.py b/omnivore8bit/hex_edit/hex_editor.py
index 7e3c19f7..91ff6d6e 100644
--- a/omnivore8bit/hex_edit/hex_editor.py
+++ b/omnivore8bit/hex_edit/hex_editor.py
@@ -408,8 +408,10 @@ def update_fonts(self):
         self.font_map.set_font()
         self.font_map.Refresh()
         pane = self.window.get_dock_pane('hex_edit.font_map')
-        pane.name = self.machine.font_mapping.name
-        self.window._aui_manager.Update()
+        if pane is not None:
+            # subclasses may not have font map pane
+            pane.name = self.machine.font_mapping.name
+            self.window._aui_manager.Update()
 
     @on_trait_change('machine.disassembler_change_event')
     def update_disassembler(self):