Flight and hotel metasearch brand Hipmunk has raised $6 million in venture funding, two years on from its large $20 million round.
The company says it will not disclose any details regarding the round.
A Form D company filing to the Securities and Exchange Commission in the US says the total amount sold in the round was $5.75 million, with a further $4.25 million still on the table.
The total funding to date is now just short of $47 million in six years.
The biggest round the company has attracted came via Oak Investment Partners in May 2014, a Series C that also included Institutional Venture Partners and Ignition Partners.
Both Institutional and Ignition contributed to a $15 million Series B in June 2012.
Hipmunk arrived on the scene in 2010, with a mission to disrupt the flight search sector (famously saying that it would take on the likes of pre-Priceline Group brand Kayak).
At the centre of its push into the industry was the creation of an "agony index", giving consumers a different way to search and compare flights on a single page.