In an earlier work we presented and upper bound on the minimum Euclidean distance for block coded phase shift keying. The bound presented is valid for any alphabet size q\geq4, but it applies only to codes with medium or high rates: codes for which |C|>(q/3)^n. Here |C| is the number of codewords and n is the block length. The bound is proven to be tight for many parameter values at high rates. In this paper we present for the case q=8 an improved upper bound. This bound is tighter at medium rates, and is valid for all rates.