dns: unknown Checker type #37

When running a DNS check with the latest amd64 version, I get the error 'dns: unknown Checker type'. HTTP-Checks are working. Am I missing something here?

{ "checkers": [{ "type": "dns", "endpoint_name": "Testing DNS", "endpoint_url": "82.211.31.248:53", "hostname_fqdn": "www.google.de", "timeout": "2s" }] }