The invention relates to a coolant circuit (1) for an internal combustion engine (2), wherein the coolant can circulate between the internal combustion engine (2) and a heat sink (3) depending upon a switchable valve (4), which is closed in the initial state during a cold start of the internal combustion engine (2), wherein the valve (4) can be switched to an at least partially opened sequential state depending on an exhaust gas mass flow emitted by the internal combustion engine (2), and wherein a control device (6) determines an integral of the exhaust gas mass flow with respect to the time and switches the valve (4) into the sequential state when an integral threshold value is exceeded.
