We compute the Hausdorff dimension of the "multiplicative golden mean shift" defined as the set of all reals in [0,1] whose binary expansion (x(k)) satisfies x(k)x(2k) = 0 for all k >= 1, and show that it is smaller than the Minkowski dimension. (C) 2011 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.