JSON POST body error when JSON contains "="

[gottlike]

I'm POSTing a JSON array of objects that can have all sorts of characters. I encountered the following error:

<Rack::QueryParser::InvalidParameterError: invalid %-encoding ({...}>

The error message stops at the point, where the property's value has === as a string. I'm assuming Rack is expecting a URL-encoded form string and it breaks somehow.

I'm using use Hanami::Middleware::BodyParser, :json, as recommended.