             // TODO: pass any JSON errors into completion function
             let json: JSON?
             if responseFilter != nil {
-                json = Utility.filteredJSON(responseFilter!, data: data)
+                json = self.dynamicType.filteredJSON(responseFilter!, data: data)
             } else {
                 json = JSON(data: data!)
             }

            // TODO: pass any JSON errors into completion function
            let json: JSON?
            if responseFilter != nil {
                json = Utility.filteredJSON(responseFilter!, data: data)
            } else {
                json = JSON(data: data!)
            }

        body: AnyObject?,
        responseFilter: String?,
        headers: [String : String]?,
        completion: swiftyCompletion?) -> NSURLSessionDataTask? {

        var deleteBody: NSData? = nil
        if body != nil {
