Music service Rhapsody on Monday announced plans to acquire Napster, most recently owned by Best Buy. Terms of the agreement were not announced, but Rhapsody indicated that Best Buy gets a minority stake in Rhapsody after the deal is done.

Rhapsody and Napster both provide subscription-based on-demand music services. They bill themselves as the two largest such services in the United States. The deal helps bolster Rhapsody against Spotify, the European-based music streaming service which earlier this year began offering access to customers in the US.

“This is a ‘go big or go home’ business, so our focus is on sustainably growing the company,” said Jon Irwin, Rhapsody’s president.

Spotify found itself in the crosshairs recently after the company instituted a policy requiring customers to sign in using Facebook. The policy shift hasn’t hurt Spotify – the company said that two million users have joined on since then, bringing the total user base to more than five million. Those two million new users are using both Spotify’s free and pay services.