Units of p-power order in principal p-blocks of p-constrained groups

Let G be a finite group having a normal p-subgroup N that contains its centralizer CG(N), and let R be a p-adic ring. It is shown that any finite p-group of units of augmentation one in RG which normalizes N is conjugate to a subgroup of G by a unit of RG, and if it centralizes N it is even contained in N.