An improved method and apparatus for mounting a brake booster on a panel with an adapter are provided, through the use of a boot having a generally cup-shaped wall defining a flange for sealing a juncture between the brake booster and the adapter, a sealing lip for sealing a juncture between the boot and the adapter, and a hole for passage of the push rod, with the hole having a periphery for sealing the juncture between the boot and the push rod. The boot includes an air intake extending through the wall of the boot between the flange and the sealing lip.