File this one under "O" for "Oops." A cleaner with the best intentions accidentally destroyed a piece of art worth more than $1 million when she removed what she thought was a "stain" from the installation. Spoiler alert: It wasn't really a stain.

The piece of art, titled "When It Starts Dripping From The Ceilings," features a series of wooden planks and a (formerly) discolored plastic bowl. The artist, the late Martin Kippenberger, intended for viewers to understand that the bowl had been discolored by water running over the pieces of wood.

Unfortunately, the bowl isn't so discolored anymore. A spokesperson from the art museum in Dortmund, Germany, remarked that "it is now impossible to return it to its original state." The cleaner was apparently unaware that she was supposed to stay at least 20 centimeters away from the works of art.

Kippenberger died at the age of 43 in 1997, but he left behind a large collection of work. Roberta Smith of the New York Times said he was "widely regarded as one of the most talented German artists of his generation." Like many of the greats, his work has grown more valuable since his death. In 2005, a Kippenberger painting went for more than $1 million.

So far, there's been no word on whether the cleaning woman will be in any legal or financial trouble for her mistake. The piece of art was on loan to the museum from a private collector, who will probably think twice before lending out any more million-dollar pieces of art. According to the AP, insurance adjusters are currently "assessing the damage." It'll be up to the owner to decide whether to approve an effort to restore the piece to something resembling its original state, or just leave it as is.