diff --git a/bone_selection_sets.py b/bone_selection_sets.py
index 7a382d755f277a6d02146f6860939aa23f25d45e..391f183aa50abc80fe83555e420f7bb78cff90b2 100644
--- a/bone_selection_sets.py
+++ b/bone_selection_sets.py
@@ -560,10 +560,12 @@ def register():
 
     # Add shortcuts to the keymap.
     wm = bpy.context.window_manager
-    km = wm.keyconfigs.addon.keymaps.new(name='Pose')
-    kmi = km.keymap_items.new('wm.call_menu', 'W', 'PRESS', alt=True, shift=True)
-    kmi.properties.name = 'POSE_MT_selection_sets_select'
-    addon_keymaps.append((km, kmi))
+    if wm.keyconfigs.addon is not None:
+        # wm.keyconfigs.addon is None when Blender is running in the background.
+        km = wm.keyconfigs.addon.keymaps.new(name='Pose')
+        kmi = km.keymap_items.new('wm.call_menu', 'W', 'PRESS', alt=True, shift=True)
+        kmi.properties.name = 'POSE_MT_selection_sets_select'
+        addon_keymaps.append((km, kmi))
 
     # Add entries to menus.
     bpy.types.VIEW3D_MT_select_pose.append(menu_func_select_selection_set)