diff --git a/sys/src/libauth/auth_chuid.c b/sys/src/libauth/auth_chuid.c
index 7ba0cfc6d..300e93f67 100644
--- a/sys/src/libauth/auth_chuid.c
+++ b/sys/src/libauth/auth_chuid.c
@@ -30,8 +30,10 @@ auth_chuid(AuthInfo *ai, char *ns)
 
 	/* get a link to factotum as new user */
 	fd = open("/srv/factotum", ORDWR);
-	if(fd >= 0)
+	if(fd >= 0){
 		mount(fd, -1, "/mnt", MREPL, "");
+		close(fd);
+	}
 
 	/* set up new namespace */
 	return newns(ai->cuid, ns);