diff --git a/collects/gui-debugger/debug-tool.ss b/collects/gui-debugger/debug-tool.ss index 3170725cae..28960e602c 100644 --- a/collects/gui-debugger/debug-tool.ss +++ b/collects/gui-debugger/debug-tool.ss @@ -895,8 +895,8 @@ (send (send (get-frame) get-step-over-button) enable (can-step-over? frames status)) (send (send (get-frame) get-step-out-button) enable (can-step-out? frames status)) (send (send (get-frame) get-resume-button) enable #t) - (send (get-frame) register-stack-frames frames already-stopped?) - (unless (empty? frames) + (when (cons? frames) + (send (get-frame) register-stack-frames frames already-stopped?) (send (get-frame) register-vars (list-ref frames (get-frame-num)))) (send status-message set-label (if (and (cons? status) top-of-stack?)