Unknown variable "H" (OpenSCAD)

[tandej]

Got a compiler error for this which prevented loading the part (a hex-socket metric bolt):

[WARNING: Ignoring unknown variable 'h' in file ../../../../.local/share/OpenSCAD/libraries/base/hex_socket/hex_socket.scad, line 48]

It points to this code:

module hex_socket2(d1,d2,b,k,s,t_min,L,l){
	h_unthreaded = (l<= L) ? 0 : l - b;
	h_threaded = (l<= L) ? l : b;

	BOLTS_check_dimension_positive(h,"l too short");

Substituting l for h seemingly fixes the problem, but I'm not familiar with the codebase so I'm not entirely confident that that's the cause.