-        self._download_webpage(login_request, None, False, 'Wrong login info')
+        try:
+            self._download_webpage(
+                self._LOGIN_URL, None, 'Logging in',
+                data=urlencode_postdata(data), headers={
+                    'Content-Type': 'application/x-www-form-urlencoded',
+                    'Referer': self._LOGIN_URL,
+                })
+        except ExtractorError as e:
+            if isinstance(e.cause, compat_HTTPError) and e.cause.code == 418:
+                raise ExtractorError(
+                    'Unable to log in: bad username or password',
+                    expected=True)
+            raise ExtractorError('Unable to log in')