Can I include a message in pre and postconditions

I have this (not (some #(= (:length %1) 0) %)) as a postcondition. Written like this it's pretty clear, but when this condition isn't met I get this:

Assert failed: (not (some (fn* [p1__17852#] (= (:length p1__17852#) 0)) %))

Which isn't very readable. Is there a way to define the message for a postcondition, or for a precondition?

Edit 1:

Following noahlz and noisesmiths suggestion, (but using an external named function):

(defn not-zero-length
  [evseq]
  (not (some (fn [item] (= (:length item) 0)) evseq)))

(defn my-func
  [evseq]
  {:post [(not-zero-length %)]}
  evseq)

(my-func '({:length 3}{:length 0}))

gives:

AssertionError Assert failed: (not-zero-length %)

Which is alot clearer.