Invalid byte sequence when parsing strange values

[thiesen]

2.1.5 :006 > TrafficSourceParser.parse("59738670.1363274811.1.1.utmgclid=CMPAurTC_LUCFQnznAod7XsAqw|utmccn=(not%20set)|utmcmd=(not%20set)|utmctr=dicas%20de%20promo%E7ao%20para%20facebook")
 => #<TrafficSourceParser::Result::Utmz utmgclid="CMPAurTC_LUCFQnznAod7XsAqw", campaign="(not set)", medium="(not set)", term="dicas de promo\xE7ao para facebook", channel="Paid Search">
2.1.5 :007 > TrafficSourceParser.parse("59738670.1371560448.1.1.utmgclid=CO_Sx-nU7bcCFYVZ7AodaAgAVg|utmccn=(not%20set)|utmcmd=(not%20set)|utmctr=CRIA%C7%C3O%20DE%20NEWSLETTER")
 => #<TrafficSourceParser::Result::Utmz utmgclid="CO_Sx-nU7bcCFYVZ7AodaAgAVg", campaign="(not set)", medium="(not set)", term="CRIA\xC7\xC3O DE NEWSLETTER", channel="Paid Search">