Replacements for almond extract?

I am going to make the NYTimes' Lemon Confit Shortbread Tart (http://www.nytimes.com/2007/01/31/din...) with meyer lemons this weekend for a friend with nut allergies, but the crust calls for 1/8 to 1/4 teaspoon almond extract, or to taste.

I doubt that taking out that miniscule amount of liquid will significantly change the texture of the crust but just to be sure, I want to find an extract replacement. Am currently thinking vanilla or coconut. Any other thoughts - what works well with lemon?