diff --git a/ffmpeg-myth.scm b/ffmpeg-myth.scm
index 03ccb1a..87a93dd 100755
--- a/ffmpeg-myth.scm
+++ b/ffmpeg-myth.scm
@@ -44,6 +44,8 @@
 	     (wtpd (close-pipe port))
 	     (xval (status:exit-val wtpd)))
 	(if (or (eqv? xval #f) (> xval 0)) (throw 'shell-command-error cmd str))
+	(cond (shell-command-log
+	       (simple-format #t "shell-command-to-string result: ~a\n" str) (force-output)))
 	str))
     ;; handler
     (lambda (key cmd str)