Get mix firmware to use kernel from compiled buildroot


In an attempt to build enable ramoops for BBB, I am rebuilding the kernel and dtb files. After I compile the kernel using ‘make linux-rebuild’ from nerves_system_bbb/.nerves/artifacts/nerves_system_bbb-portable-2.18.1, I see the changed kernel at blinky/deps/nerves_system_bbb/.nerves/artifacts/nerves_system_bbb-portable-2.18.1/images/zImage. mix firmware && mix firmware.burn doesn’t pick up and write the changed kernel to sdcard. Is this expected. Are there any options or an easy method to get it to pick up the modified kernel?