Method for operating an internal combustion engine, wherein the internal combustion engine is operated by an air-fuel mixture comprising a fuel mixture and air, wherein the fuel mixture comprises a first fuel, preferably natural gas, and hydrogen as a second fuel different from the first fuel, wherein a hydrogen content of the fuel mixture is determined, and at least an ignition timing is adapted as a function of the hydrogen content of the fuel mixture independent of a target power output of the internal combustion engine,
wherein the higher the amount of hydrogen in the fuel mixture the later the ignition timing is set for at least partially compensating a shift of a center of combustion due to higher flame speed of hydrogen compared to the first fuel.