Please see https://github.com/ziglang/zig/issues/544#issuecomment-36396... and https://github.com/ziglang/zig/issues/663. In particular, `For every codepoint of zig source code, it is an error for the codepoint to be one of U+0000-U+0009, U+000b-U+001f, U+007f, U+0085, U+2028, U+2029`. Hard tab is U+0009, which is called out as specifically an error. This could just be stale docs, but it's linked to from the wiki as well: https://github.com/ziglang/zig/wiki/FAQ#why-does-zig-fmt-hav.... Again, if this is all old, please ignore (and maybe make it a priority to update?). But the general tone is: "No tabs, only spaces"