diff --git a/data/mods/Aftershock/maps/mapgen/millyficent_lab.json b/data/mods/Aftershock/maps/mapgen/millyficent_lab.json
index 5a49d6effcd0b..6c044f0d6e11d 100644
--- a/data/mods/Aftershock/maps/mapgen/millyficent_lab.json
+++ b/data/mods/Aftershock/maps/mapgen/millyficent_lab.json
@@ -200,7 +200,7 @@
     "method": "json",
     "om_terrain": [ "mortuary_2story_second" ],
     "object": {
-      "fill_ter": "t_open_air",
+      "fill_ter": "t_floor",
       "rows": [
         "________________________",
         "________________________",