diff --git a/time.zig b/time.zig
index debbcd03d1d74b42c046608e036ff4d734cb831e..e85e002d1b9f933b5518b27315c2b31edfef287a 100644
--- a/time.zig
+++ b/time.zig
@@ -264,6 +264,8 @@ pub const DateTime = struct {
                 ':',
                 '-',
                 '.',
+                'T',
+                'W',
                 => {
                     try writer.writeAll(&.{c});
                     s = i + 1;