We evaluate new observational constraints on the two-parameter scale-dependent spectral index predicted by the running-mass inflation model by combining the latest cosmic microwave background anisotropy measurements with the recent 2dF Galaxy Redshift Survey data on the matter power spectrum, with Lyman α forest data and finally with theoretical constraints on the reionization redshift. We find that present data still allow significant scale dependence of n, which occurs in a physically reasonable regime of parameter space.