Artworks in the Russian avant-garde style have long been targeted by forgers. But recent discoveries in three major European museum collections shows just how prevalent these fakes are.

The state collection of North Rhine-Westphalia in Düsseldorf and the Albertina museum in Vienna have both recently found that they’ve been housing forgeries among their holdings. The German Handelsblatt reports that the 1915 Constructivist work Black Rectangle, Red Square, thought to be by Kazimir Malevich and estimated at around $94 million, was actually painted between 1972-75, according to recent scientific research. (Malevich died in 1935.)

To add insult to injury, the painting was even used as the Düsseldorf museum’s logo. It ended up in the museum’s collection in 2014 as part of a donation from a private foundation that also owned some 40 drawings by the Russian Suprematist.

The museum was aware of the work’s questionable provenance and ordered tests shortly after the work was donated. But in the summer of 2015, before the results came in, the new acquisition was put on display to substantial fanfare, heightened by a recent $60 million sale of a similar Malevich painting at Sotheby’s.

Two years later, in an announcement published on the museum’s website on Friday, it acknowledged that the results indicate the work is a forgery. It explained that an analysis of the canvas fibers and pigments suggest that the work could not have been painted before 1950, and most likely originated between 1972 and 1975.

The Technical University of Cologne and the University of Kiel conducted the research, and other comparisons were made to an authentic Malevich painting in the US. The results match early public appearances of the artwork, which first turned up in literature and catalogues in 1975.

“As hard as it is, the fake must be acknowledged,” the director of the Kunstsammlung Nordrhein-Westfalen, Susanne Gaensheimer, said in a statement. “The work came to us as a gift from a private collection, and was a generous gift made with best intentions. The result of the appraisals hits us very hard. Unfortunately we also know that forgeries of Malevich’s work are not isolated cases. For this reason, the museum commissioned the two reports under my predecessor Marion Ackermann. It is important to deal with this situation transparently.”