We extract a new value b = 0.0205±0.0017 fm² of the slope of the neutron form factor G_En(q²) at q² = 0 compatible with deuteron properties by using a linear relation between b and A²_S(1+η²) we found for a class of nonlocal potential models having the experimental values of both r_D and Q. Another model dependent value b ^MHKZ = 0.0206±0.0014 fm²
, which is also compatible with deuteron properties, has been determined by applying "constrained" unitary transformations to the local MHKZ potential model. The sensitivity of a small changes in the experimental values used for r_D and Q on the value obtained for b is also investigated.