diff --git a/scsh/syscalls.scm b/scsh/syscalls.scm
index 234881f..b4d6e14 100644
--- a/scsh/syscalls.scm
+++ b/scsh/syscalls.scm
@@ -1,4 +1,3 @@
-
 ;;; POSIX system-call Scheme binding.
 ;;; Copyright (c) 1993 by Olin Shivers.
 
@@ -800,7 +799,10 @@
 
 (define (alist->env-vec alist)
   (list->vector (map (lambda (var.val)
-		       (string-append (car var.val) "=" (cdr var.val)))
+		       (string-append (car var.val) "="
+				      (let ((val (cdr var.val)))
+					(if (string? val) val
+					    (string-join val ":")))))
 		     alist)))
 
 ;;; ENV->ALIST