One of the paintings by Dutch painter Piet Mondrian has decades Hanging upside down in the Kunstsammlung Nordrhein-Westfalen Museum in Düsseldorf. The German Museum revealed this at a press conference at the opening of an exhibition honoring Mondrian’s 150th birth. The museum added the painting to its collection in 1980.

Curator Susan Meyer Bowser believes there are several reasons to believe that the painting was incorrectly hung.

The board consists of several horizontal and vertical colored strips. In a photo taken in his studio shortly after Mondrian’s death in 1944, the artwork can be seen on an easel. The strips are located close together at the top of the board.

This is also the case with an almost identical painting that hangs in the Center Pompidou in Paris.

In the German Museum, the painting is rotated 180 degrees, so that the lines close to each other are at the bottom. The museum has no plans to flip the artwork now that the flaw has been discovered.

Watch the trailer for the exhibition in which the painting can be viewed here: