diff --git a/plugins/lua/sort/world.lua b/plugins/lua/sort/world.lua
index a4cf6c0e5..65263cb98 100644
--- a/plugins/lua/sort/world.lua
+++ b/plugins/lua/sort/world.lua
@@ -44,6 +44,7 @@ end
 
 local function cleanup_artifact_vectors(data)
     local vs_world = dfhack.gui.getDFViewscreen(true)
+    if not df.viewscreen_worldst:is_instance(vs_world) then return end
     vs_world.artifact:assign(data.saved_original)
     vs_world.artifact:resize(data.saved_original_size)
     vs_world.artifact_arl:assign(data.saved_flags)