diff --git a/src/building_floorplan.cpp b/src/building_floorplan.cpp
index a779eefa6..b0c3babfb 100644
--- a/src/building_floorplan.cpp
+++ b/src/building_floorplan.cpp
@@ -2193,7 +2193,15 @@ void building_interior_t::assign_door_conn_rooms(unsigned start_ds_ix) {
 			for (unsigned r = rooms_start; r < rooms_end; ++r) {
 				if (rooms[r].contains_pt(test_pt)) {ds_room_ix = r; break;}
 			}
-			assert(ds_room_ix >= 0); // adj room must be found
+			if (ds_room_ix == -1) { // adj room not found
+				// can only happen with complex floorplan buildings where a wall ends exactly at a doorway so that neither room contains the point
+				test_pt[!d->dim] = d->d[!d->dim][0]; // choose edge of door rather than center
+
+				for (unsigned r = rooms_start; r < rooms_end; ++r) {
+					if (rooms[r].contains_pt(test_pt)) {ds_room_ix = r; break;}
+				}
+				assert(ds_room_ix >= 0);
+			}
 			d->conn_room[s] = ds_room_ix;
 		} // for s
 		assert(d->conn_room[0] != d->conn_room[1]); // can't be connected to the same room on both sides