diff --git a/scsh/newports.scm b/scsh/newports.scm
index 78c9d48..4f64c91 100644
--- a/scsh/newports.scm
+++ b/scsh/newports.scm
@@ -542,7 +542,7 @@
 (define (flush-all-ports)
   (weak-table-walk
    (lambda (i fdport)
-     (if (and fdport (output-port? fdport)) (flush-fdport fdport)))
+     (if (and fdport (open-output-port? fdport)) (flush-fdport fdport)))
    fdports))
 
 ;;; Extend R4RS i/o ops to handle file descriptors.