The dependence of Compton profiles calculated from X alpha wavefunctions on the choice of exchange parameter alpha is discussed in the light of the non-locality correction of Lam and Platzman (1974) and Tong and Lam (1978). The Compton profiles for neon and argon, using the alpha values suggested by Gopinathan (1977), are reported. The Compton profile for neon with this alpha value agrees very well with the Hartree-Fock profile if the non-locality corrections is included. The agreement for the case of argon is not so good. The possible origins of the discrepancies for argon are discussed.