Strange behavior JSON data

In a data extension we receive some basic JSON data. Like this:

[{"adressoort": 1,"is_ontvangstadres": "true","persoonsnaam": "Test","bedrijfsnaam": null,"postcode": "01234AB","straatnaam": "Test","huisnummer": "1","huisnummer_toevoeging": null,"woonplaats": "","land": "NL"}

]

Based on this data with some additional data from other fields in the data extension we concat a URL like this:

{{#adressenInformatie}}{{#if adressoort=="1"}} %%[ var @landJSON, @postcodeJSON set @landJSON = TreatAsContent('{{land}}') set @postcodeJSON = TreatAsContent('{{postcode}}') set @link_barcodeURL = concat('https://OUR-URL',@barcode,'- ',@landJSON,'-',@postcodeJSON) ]%%<a class="link" href="%%=RedirectTo(@link_barcodeURL)=%%" target="_blank" titel="Btn %%=v(@barcode)=%%" alias="BtnStandaardINT" style="color: #3D43E6; text-decoration: none;">%%=v(@barcode)=%%</a>{{/if}} {{/adressenInformatie}}

The outcome of the URL is this: https://OUR-URL/123456789-NL-1234AB

As you can see the 0 (zero) before the 1234AB has stripped out. Why is that? And how can we fix this?