teleport tubes causing warning

[SwissalpS]

WARNING[Server]: Passing `fields` with number values is deprecated and may result in loss of precision. (at data/world/worldmods/pipeworks/tubes/teleport.lua:43)

I haven't recreated it yet in singleplayer, noticed on pandorabox after having regular lag-spikes that may or may not be related to tp-tubes.
Some indications suggest it might.

[SwissalpS]

changing tubes/teleport.lua#39 to

local fields = { version = tostring(tube_db_version) }

does get rid of the warning.