Congolese citizen Bienvenu Mbutu Mondondo and a black rights group have filed a complaint against the 1931 book by celebrated Belgian author Herge.

Judges postponed Wednesday’s scheduled hearing after a plaintiff withdrew from the case, delaying a new hearing until next week.

Plaintiffs have said the book about the adventures of the intrepid reporter and his dog Snowy in Belgian Congo, now the Democratic Republic of Congo, should at least be relegated to the adult sections of libraries.

Herge, real name Georges Remi (1907-1983), justified the book by saying it was merely a reflection of the naive views of the time. Some of the scenes were revised for later editions.