and this one

src/libhttpd/hio.c

diff --git a/src/libhttpd/hio.c b/src/libhttpd/hio.c
index b5339ed..b404cf4 100644
--- a/src/libhttpd/hio.c
+++ b/src/libhttpd/hio.c
@@ -375,6 +375,7 @@
 	f.flush = fmthflush;
 	f.farg = h;
 	f.nfmt = 0;
+	fmtlocaleinit(&f, nil, nil, nil);
 	n = fmtvprint(&f, fmt, args);
 	h->pos = f.to;
 	return n;