The Supreme Court of Canada annulled the results of a closely contested riding from last spring’s election on Friday.

The Montreal-area riding of Terrebonne was initially declared for the Bloc Québécois until a judicial recount found the Liberals had won the seat by one vote.

But Nathalie Sinclair-Desgagné, the Bloc candidate, called on the courts to annul the results and call a new election after CBC News reported that a voter had their mail-in ballot returned to them due to a misprint on the return envelope.

The voter, Emmanuelle Bossé, had marked her ballot for the Bloc.

Elections Canada acknowledged the error but said the results had already been finalized.

Liberal Tatiana Auguste was sworn in as the riding’s MP following the recount and has been sitting as Terrebonne’s representative since.

In October, a Superior Court judge rejected Sinclair-Desgagné’s call for a do-over, arguing that a postal code mishap amounted to “human error” and does not constitute an irregularity as defined under federal electoral law.

The top court overturned that ruling after hearing arguments earlier in the day.