Council of Trent, On Justification, Canon XXIV:

If any one saith, that the justice received is not preserved and also increased before God through good works; but that the said works are merely the fruits and signs of Justification obtained, but not a cause of the increase thereof; let him be anathema.

It’s funny: I talk to a lot of Catholics, and when I tell them, “We’re saved on the merits of Christ’s work alone,” they nod their heads. Most modern Catholics don’t know their history well enough to know that this blatantly contradicts their church’s 19th ecumenical council in the 16th century. The number of heretical canons that came out of this council are truly astounding when you read them.