diff --git a/contrib/20.repl/repl.scm b/contrib/20.repl/repl.scm
index f745ce4e..60411749 100644
--- a/contrib/20.repl/repl.scm
+++ b/contrib/20.repl/repl.scm
@@ -11,7 +11,9 @@
    (else
     (begin
       (define (readline str)
-        (if (tty?) (display str))
+        (when (tty?)
+          (display str)
+          (flush-output-port))
         (read-line))
       (define (add-history str)
         #f))))