post_install() {
    EXTRAMODULES='extramodules-4.9-lts'
    depmod $(cat /usr/lib/modules/$EXTRAMODULES/version)
}

post_upgrade() {
    EXTRAMODULES='extramodules-4.9-lts'
    depmod $(cat /usr/lib/modules/$EXTRAMODULES/version)
}

post_remove() {
    EXTRAMODULES='extramodules-4.9-lts'
    depmod $(cat /usr/lib/modules/$EXTRAMODULES/version)
}