diff --git a/lib/hx509/ks_dir.c b/lib/hx509/ks_dir.c
index 9ce9b5c8e..0d07aa95c 100644
--- a/lib/hx509/ks_dir.c
+++ b/lib/hx509/ks_dir.c
@@ -113,7 +113,9 @@ dir_iter_start(hx509_context context,
 	free(d);
 	return errno;
     }
+#ifndef _WIN32
     rk_cloexec(dirfd(d->dir));
+#endif
     d->certs = NULL;
     d->iter = NULL;