Systems and methods are disclosed for adjusting the spark timing of an internal combustion engine. According to at least one aspect of the present disclosure, the system includes an exhaust gas recirculation (EGR) system for recirculating exhaust gas flow from at least one primary EGR cylinder of an engine into an intake system prior to combustion. According to at least one other aspect of the present disclosure, the method includes estimating a dynamic EGR fraction of exhaust gas directed into the intake system via the EGR system, estimating a steady-state EGR fraction of exhaust gas directed into the intake system at the changed mass air flow rate, computing a difference between the dynamic fraction and steady-state fraction to determine a change in EGR fraction, and applying a gain factor to the change in EGR fraction to determine a desired spark timing adjustment.