That’s usually how it’s done with words that end in one consonant when adding a suffix that starts with a vowel, so as not to change the pronunciation of the short vowel in the root word due to english’s rules around long and short vowels. See also map->mapped, bat->batted, tap->tappable etc
English inserts an additional ‘p’ in some cases; for precedent consider “stoppable”, “unflappable”, “skippable”.