I must be going mad!

Given this defun: (defun jmh-test-func () (let (tv) (setq tv '((?a) (?b))) (push "testme" (cdr (assoc ?a tv))) tv)) Why does the value returned keep accumulating data from previous calls? First time: => ((?a "testme") (?b)) Next time: => ((?a "testme" "testme") (?b)) ...and so on... => ((?a "testme" "testme" "testme") (?b)) => ((?a "testme" "testme" "testme" "testme") (?b)) It's driving me crazy! I was under the impression let created a local binding which was destroyed when the let statement went out of scope? I tried edebugging, and before the setq the value of tv is nil, and immediately after the setq tv has the specified value the first time, but the *previous* value for each subsequent call. Clearly, I must be missing something... :) When I re-eval the defun, xemacs "forgets" the old values, and the insanity starts all over! Any insight? -- Josh Huber