Expedia is ready to take on Airbnb by adding more house listings to its HomeAway unit.

“Phase one was just getting the platform working and getting people online,” said Expedia Chief Executive Officer Mark Okerstrom in an interview, according to Bloomberg. “Phase two is about property acquisition.”

Expedia acquired HomeAway in 2015, and has spent the last three years improving the site’s technology and boosting its online offerings. While Expedia doesn’t have a specific number of listings it wants to add over the coming years, Okerstrom did bring up the numbers his competitors have already hit.

“You could look at what’s out there, and some of the other numbers that other players in the industry have mentioned. I think that’s the beginning,” he said.

Expedia’s HomeAway has 1.7 million bookable online listings, while rival Booking Holdings — formerly Priceline — and Airbnb both have around 5 million. In addition, HomeAway currently generates about $300 million in revenue per quarter (about 10 percent of Expedia’s total), with profit at the unit doubling in the last quarter.

As for its competitors, last month, it was reported that Airbnb wants to go public on June 30 of next year and aims to have an IPO before 2020. And just this week, corporate travel platform Concur, owned by SAPannounced it has integrated listings from Airbnb into its platform. Concur said that Concur Travel will now show listings available from Airbnb directly within its platform, making it the only corporate travel solution to do so, the company said. Airbnb listings will now appear alongside traditional hotels within the online travel booking solution, operated by SAP Concur.

For its own part, Booking recently invested $500 million in Chinese ride-hailing company Didi Chuxing. According to reports, Booking will offer Didi’s on-demand car services through its Booking.com apps via an integration. In addition, Didi customers can book hotels through Booking.com and its sister site Agoda.