If you need a good jolt of holiday spirit, or just some unpretentious fun, look no further than “Irving Berlin’s White Christmas,” the new-fangled, old-fashioned jukebox musical culled from the popular 1954 Bing Crosby-Danny Kaye film.

The formula is simple: Take the familiar narrative and augment it with songs from Berlin’s vast catalog — turning it into smart, effortless entertainment that succeeds from the sparkling, period-style overture to its ice-skating finale, replete with snow falling on the audience.

Talk about an instant classic.

What’s most delightful is how adapters David Ives and Paul Blake have taken the corny plot about a song-and-dance team who save the Vermont inn of their World War II commander and make it as welcome as a cup of warm cocoa on a cold night.

They retain the film’s most memorable moments, such as the “Sisters” number, but add new ones, such as show-stopping takes on “Blue Skies” and “I Love a Piano.”

The dance numbers, staged by Randy Skinner, are big and brash in the style of “42nd Street,” not a bad model to follow.

Director Walter Bobbie (best known for the reductive version of “Chicago"), keeps the action moving at a brisk pace.

He is assisted immeasurably here by the handsome designs of Anna Louizos that enhance the cinematic flow, and by Carrie Robbins’ colorful, humorous period costumes.

Add to this Larry Blank’s brash period-style orchestrations and you have a sure-fire evocation of the movie musicals that were little more than hit-parade showcases for Berlin’s legendary songwriting skills, but, happily, never pretended to be anything else.

Wisely Stephen Bogardus never evokes Crosby as crooner Bob Wallace, but puts his own laid-back spin on the role.

Michael Gruber is enormously charming as his hoofing partner Phil Davis.

Nadine Isenegger and Kerry O’Malley are nicely cast as their love interests, the sisters Judy and Betty Haynes.

And there’s a delightful turn by Broadway veteran Karen Morrow, whose brassiness hasn’t been diminished by time.

She’s known for starring in flop musicals, so it’s great to see her in one that can only be considered a smash.