diff --git a/scheme/big/more-port.scm b/scheme/big/more-port.scm
index 02a3de0..38c205c 100644
--- a/scheme/big/more-port.scm
+++ b/scheme/big/more-port.scm
@@ -325,10 +325,8 @@
 		  (buffer-set! buffer start next)
 		  1)))))
    (lambda (port)
-     (if (or (port-pending-eof? port)
-	     (source-data-buffer (port-data port)))
-	 #t
-	 ((source-data-ready? (port-data port)))))))
+     (error "Peek on char-source is not implemented. Complain to the scsh implementors"))))
+             
 
 (define (buffer-set! buffer index char)
   (if (string? buffer)