Comparison of parameter constraints from Planck+WP+highL for three CIB foreground models with different restrictions on the CIB spectral index γ^CIB (assumed to be the same in the 143 and 217 GHz channels). The top six panels show cosmological parameter constraints on n_s (top left) in the base ΛCDM model and on single-parameter extensions of the ΛCDM model. These are very stable to the modelling of the CIB. Each sub-plot is obtained from an independent analysis of that model with CosmoMC. The lower six panels show the constraints on a subset of the foreground parameters in the base ΛCDM model, some of which change significantly.