It's true that what you're suggesting may be more "proper," but both ways of saying it are technically correct*. It can be a regional thing, and saying it that way may be intentional on the part of the translators (to show some of the quirks of ootsuka's speech patterns that wouldn't otherwise translate to English).
*Just like how you can say "I'll learn you a lesson" in the south(?) of the US, instead of the more common "I'll teach you a lesson."
