A Swedish girl received an unexpected birthday surprise when police arrived at her door with reports that she had been displaying a symbol of the Islamic State.

To mark the big day, Sarah Ericsson hung two balloons by her window to reveal her age: 21. But from outside the house, the numbers were reversed, and passers-by mistook it for the letters 'IS.'

Ericsson was shocked upon hearing this from the police, as neither she nor anyone else she had spoken to had noticed the coincidence.

To prevent any further confusion, she was asked to remove the balloons, and was even wished a happy birthday by one of the officers.