Empty POST on IE 9

form.html

<form class="login-form" role="form" action="https://DOMAIN/login" method="post">
    <input type="hidden" name="_token" value="<TOKEN>">

    <fieldset>
        <div class="form-group">
            <label class="control-label">Email</label>
            <input type="email" name="email" class="form-control" required autofocus value="">
        </div>
        <div class="form-group">
            <label class="control-label">Password</label>
            <input type="password" name="password" class="form-control">
        </div>
    </fieldset>

    <input type="submit" value="Login" class="btn btn-primary">
</form>