SICP in Clojure: Chapter 1, Exercise 28

This is my Clojure solution to Chapter 1, Exercise 28:

(ns sicp.ch1.ex28)

(defn square-check
  [n m]
  (let [r (rem (* n n) m)]
    (if (and (not (or (= 1 n) (= (- m 1) n)))
             (= 1 r))
      0 r)))

(defn expmod
  [base exp m]
  (cond (zero? exp) 1
        (even? exp) (square-check (expmod base (/ exp 2) m) m)
        :else       (rem (* base (expmod base (dec exp) m))
                         m)))

(defn miller-rabin-test
  [n]
  (letfn [(try-it [a]
            (= (expmod a n n) a))]
    (try-it (inc (rand-int (dec n))))))

(def primes [1009 1013 1019 10007 10009 10037 100003 100019 100043
             1000003 1000033 1000037])

(every? miller-rabin-test primes) ; => true

(def carmichael-numbers [561 1105 1729 2465 2821 6601])

(map miller-rabin-test carmichael-numbers) ; => sometimes false