diff --git a/mapgen.lua b/mapgen.lua
index eef8461..9b0e9b0 100644
--- a/mapgen.lua
+++ b/mapgen.lua
@@ -110,6 +110,7 @@ nether.register_portal("nether_portal", {
 			return existing_portal_location, existing_portal_orientation
 		else
 			destination_pos.y = nether.find_surface_target_y(destination_pos.x, destination_pos.z, "nether_portal", player_name)
+			if not destination_pos.y then return nil end
 			if minetest.is_protected(destination_pos, "") then return nil end
 			return destination_pos
 		end