Perhaps it was the bumpy ground.

Or maybe Gossip Girl star Leighton Meester is still mastering the art of walking in high heels.

The actress nearly came a cropper yesterday as she tottered around in a pair of yellow stilettos before losing her footing (and one of her shoes).

Unsteady as she goes: Leighton Meester loses her footing in a pair of vertiginous yellow heels on the set of Gossip Girl in New York yesterday

Laughing at herself: The actress saw the funny side of things as she hobbled around on the cobbled pavement

Leighton, who plays high society queen bee Blair Waldorf in the hit U.S. show, was on set when the incident happened.

Dressed in a green pea coat and spotted scarf, the 23-year-old actress was seen laughing at herself after her mishap.

But at first it appeared she might have stubbed her toes, as she hobbled around on the cobbled pavement.

Keeping her feet on the ground: Co-star Blake Lively films a cab scene

Also on location in Brooklyn, New York, was Meester's co-star Blake Lively, 22, who plays Serena van der Woodsen, the friend and occasional competitor of Waldorf.

Lively was filming a cab scene, dressed in a sheepskin coat and knee-high boots.

Luckily for her, she managed to keep both her feet firmly on the ground.