The solubility of carbon dioxide in binary mixtures of water and methanol containing up to 12.37 mass % methanol has been measured at temperatures between 298 K and 333 K at atmospheric pressure. The solubility increases with increasing methanol content, but the influence is, at least at low temperatures, much smaller than linear interpolation would suggest. Employing the van't Hoff equation for ideal solutions, a correlation has been proposed that fits the measurements for up to 8.16 mass % methanol in water.