Online music store Napster Inc. on Thursday raised its revenue forecast for the fiscal fourth quarter, due to "robust" growth in its subscription service.

The Los Angeles-based company said it now expects revenues of about $15 million for the quarter ending March 31, instead of its previous estimate of $14 million.

"We are raising our guidance based on robust growth in our subscription service," Chris Gorog, chairman and chief executive of Napster, said in a statement.

In February, Napster launched its rent-a-tune service, called Napster To Go, and a $30 million marketing campaign to convince consumers that it's better to rent than own the music they like to take with them on the road.

With Napster To Go, subscribers pay $14.95 a month for unlimited downloads from the company's store of a million song tracks. The music plays on any device that supports Microsoft Corp.'s Janus copy-protection software found in Windows Media Player 10.

Gorog said the marketing campaign was delivering strong returns by generating "unprecedented interest in both our regular and portable music subscription offerings."

In addition, a "positive reception" in the market to compatible music players from Creative Technology Ltd., Dell Inc. and Iriver Inc. have also helped drive sales, Gorog said.