It is sometimes of interest to calculate laminar flame speeds under conditions where autoignition is possible. Determining laminar flame speeds using simulation assumes flames are freely propagating, an assumption that is not valid when autoignition does occur. If laminar flame speed tables are generated for use in CFD, it is useful to have extrapolated laminar flame-speed values under autoigniting conditions to allow CFD to operate smoothly and avoid discontinuities while calculating flame-propagation properties. An option is presented in the Run Calculations panel to ‘Detect if auto-ignition occurs’. If this option is selected, first a closed homogeneous batch reactor simulation is performed for the unburnt gas temperature, pressure, and composition specified for the flame speed case. When choosing this option, the typical residence time of unburnt gases from inlet to the flame front is requested, so that autoignition can be tested for in this timeframe. An ignition definition of 20 K rise from initial temperature is used by default, which can be modified in the Run > Output subpanel of the Preferences panel. If autoignition is determined to occur, flame speeds are not simulated; for such conditions, flame speeds are linearly extrapolated if there are enough available calculated flame speeds from nearby operating conditions. An example of using this option is presented in the flame_speed_table__methane tutorial project, and explained in the Forte Tutorials, available from the Ansys Help website.