# XO1306: import from a module xo.mod does not require

An import path whose first element is a host name (`github.com/acme/billing/invoice`) names a package of another module, and that module must be required in xo.mod so its version is selected and locked. `xo get <module path>` adds the latest version; `xo mod tidy` adds a requirement for every such import. See core 4.1, 4.2, and decision 0086.

## Example

```xo
use github.com/acme/billing/invoice   // xo.mod has no require for it

fn total() -> Int { invoice.total() }
```

## Fix

```xo
// xo get github.com/acme/billing adds to xo.mod:
require github.com/acme/billing v1.4.0
```

Run `xo explain XO1306` for this text in a terminal, or see
[section 10.6 of the specification](../../spec/core/#106-diagnostic-codes).