A flag mix-up caused Canada a bit of embarrassment today — day one of a state visit by the king and queen of Belgium, the first such visit in over 40 years.

Belgian journalist Wim Dehandschutter was the one who first pointed out that the flag marking a tree Belgium's Queen Fabiola planted on the grounds of Rideau Hall back in 1977 was actually Germany's flag.

Oeps, foutje. Canadezen signaleren boom die koningin Fabiola in 1977 heeft geplant in Ottawa tijdens eerste Belgisch staatsbezoek met Duits(!) vlagje. Nadat Belgische media hen daar attent op maken, grijpen ze in. <a href="https://twitter.com/hashtag/BelCan2018?src=hash&ref_src=twsrc%5Etfw">#BelCan2018</a> <a href="https://t.co/pSPIqZMzaJ">pic.twitter.com/pSPIqZMzaJ</a> —@WDehandschutter

Both flags feature black, red and yellow or gold bands, but Belgium's stripes are vertical while Germany's are horizontal.

"While we were preparing for the tree planting ceremony on the grounds of Rideau Hall, it was brought to our attention that there was a mix up with a small flag," said Marie-Ève Létourneau, a spokesperson for Rideau Hall.