diff --git a/unix/uxsftpserver.c b/unix/uxsftpserver.c
index 7c485a4a..534f6965 100644
--- a/unix/uxsftpserver.c
+++ b/unix/uxsftpserver.c
@@ -650,8 +650,9 @@ static void uss_readdir(SftpServer *srv, SftpReplyBuilder *reply,
                 tm = *localtime(&st.st_mtime);
 
                 longnamebuf = dupprintf(
-                    "%s %3u %-8s %-8s %8"PRIu64" %.3s %2d %02d:%02d %s",
-                    perms, (unsigned)st.st_nlink, user, group, st.st_size,
+                    "%s %3u %-8s %-8s %8"PRIuMAX" %.3s %2d %02d:%02d %s",
+                    perms, (unsigned)st.st_nlink, user, group,
+                    (uintmax_t)st.st_size,
                     (&"JanFebMarAprMayJunJulAugSepOctNovDec"[3*tm.tm_mon]),
                     tm.tm_mday, tm.tm_hour, tm.tm_min, de->d_name);
                 longname = ptrlen_from_asciz(longnamebuf);