Norway's right-wing coalition on Sunday took in a small centre-right party, but remains a minority government and will continue the search for the parliamentary majority needed to ensure it can pass laws.
Conservative Prime Minister Erna Solberg, who has been in power since 2013, secured a narrow victory with her coalition partner, the anti-immigration Progress Party, in September elections.
The new deal with the Liberal Party was announced by the three party chiefs after 10 days of negotiations.
The distribution of ministerial portfolios between the three parties will take a little longer to agree, but an announcement is expected by Friday.
Even with the addition of the eight Liberal members of parliament, the coalition government remains short of a parliamentary majority, with 80 of the 169 seats in the chamber, and will have to continue the search for partners.
Traditional ally the Christian Democrats, who also have eight deputies, have so far resisted all offers to enter the current government.