nginx rewrite trying to find a file with query string included

Question

I am trying to map friendly URLs to files in a legacy app. There is a file which will receive an action as a parameter to render different sections.

I think that my rewrite condition is wrong because nginx is trying to locate the file including the query string. Here is a section of my conf:

http {
    ...
    map $request_uri $legacy_rewrite {
        ...
        ~^/informativos$ /painel.php?act=ver_informativos;
        ...
    }

    server {
        ...
        location / {
            if ($legacy_rewrite) {
                rewrite ^/(.*)$ $legacy_rewrite break;
            }
        }
    }
}

The problem is that I get this error:

[error] 1132019#0: *28724 open() "[my_app_path]/painel.php?act=ver_informativos;"  failed (2: No such file or directory)

How should I write this rewrite so nginx would understand that I am referencing painel.php?