How to compare two Joda time Periods

It does not seem straighforward.

I am trying this:

@Override
public int compare(Period o1, Period o2) {
    return o1.toStandardDays().getDays() > o2.toStandardDays().getDays() ? -1 : (o1.toStandardDays().getDays() == o2.toStandardDays().getDays() ? 0 : 1);
}

But I get this exception:

java.lang.UnsupportedOperationException: Cannot convert to Days as this period contains months and months vary in length
    at org.joda.time.Period.checkYearsAndMonths(Period.java:1455)
    at org.joda.time.Period.toStandardDays(Period.java:1314)

I hoped Peroid would have an isLongerThan(Period p) method.