The last field is not present in protocol versions older than 2.3 (see http://www.gpsinformation.org/dale/nmea.htm#GLL), so lines from old receivers will not be parsed correctly. I just added support for optional fields (cloudyourcar/minmea repository), please do the following:

* merge with upstream
* fix the format string in `minmea_parse_ggl` to `"tfdfdTc;c"`
* write separate unit tests for both old and new version of the frame.