diff --git a/scsh/scsh.scm b/scsh/scsh.scm
index 393323d..3e74c45 100644
--- a/scsh/scsh.scm
+++ b/scsh/scsh.scm
@@ -82,8 +82,8 @@
 			     (for-each (lambda (fd) (dup w fd)) from)
 			     (close w))) ; Unrevealed ports win.
 			 froms pipes)
-	       (if (pair? maybe-thunk)
-		   (call-terminally (car maybe-thunk)))))
+	       (if maybe-thunk
+		   (call-terminally maybe-thunk))))
 	proc))))
 
 (define (tail-pipe a b)