1 files changed, 2 insertions, 0 deletions
diff --git a/lib/xwrap.c b/lib/xwrap.c
index 89488acf..66972f2b 100644
--- a/lib/xwrap.c
+++ b/lib/xwrap.c
@@ -357,6 +357,8 @@ int xdup(int fd)
 // old one. (We should never be called with stdin/stdout/stderr closed, but...)
 int notstdio(int fd)
 {
+  if (fd<0) return fd;
+
   while (fd<3) {
     int fd2 = xdup(fd);