There is provided a combustor comprising a dome and a shell extending from the dome defining a combustion chamber. A dome heat shield is mounted to the dome inside the combustion chamber. A front heat shield is mounted to the shell and spaced therefrom. The dome heat shield has a lip extending generally away from the dome heat shield and generally parallel to the shell and spaced inwardly of the front heat shield to define a gap between the lip and the front heat shield. The front heat shield has a leading edge opposite the lip. The combustor has impingement holes extending through the shell and disposed to direct impingement cooling jets to the upstream portion of the front heat shield. The leading edge, of the front heat shield has at least one scallop defining an opening and disposed to allow the impingement cooling jets to impinge directly on a portion of the peripheral lip adjacent the scallop.