How to bind a checkbox in Echo framework?

I have a simple form which I want to bind on the post request.

Here is the form:

<form method="post" action="/post">
    <input type="text" name="name" placeholder="name"><br>
    <input type="checkbox" name="agree"><br>
    <button type="submit">submit</button>
</form>

I'm trying to bind it in such a stuct:

type PostForm struct {
    Name  string
    Agree bool
}

Here is the whole code:

package main

import (
    "github.com/labstack/echo/v4"
    "html/template"
    "io"
    "log"
    "net/http"
)

type Template struct {
    templates *template.Template
}

func (t *Template) Render(w io.Writer, name string, data interface{}, _ echo.Context) error {
    return t.templates.ExecuteTemplate(w, name, data)
}

type PostForm struct {
    Name  string
    Agree bool
}

func main() {
    e := echo.New()
    e.Debug = true
    e.Renderer = &Template{
        templates: template.Must(template.ParseGlob("./templates/*.gohtml")),
    }
    e.GET("/", func(c echo.Context) error {
        return c.Render(http.StatusOK, "index.gohtml", nil)
    })
    e.POST("/post", func(c echo.Context) error {
        var form PostForm
        err := c.Bind(&form)
        if err != nil {
            return c.String(http.StatusInternalServerError, err.Error())
        }
        return c.JSON(http.StatusOK, form)

    })

    log.Fatalln(e.Start(":3000"))
}

When I do post request with unchecked Agree field, it works fine:

{
  "Name": "sdfgsdfg",
  "Agree": false
}

But when I send the post with checked checkbox, there is an error:

code=400, message=strconv.ParseBool: parsing "on": invalid syntax, internal=strconv.ParseBool: parsing "on": invalid syntax

What I'm doing wrong?

Here is the repo on github with all code: https://github.com/max-block/q__echo_bind_checkbox