As others have said, put it in a zip lock bag and then into the freezer or refrigerator. If you have high humidity and you do not have a package of desiccant available the put it in the refrigerator.

I store my film in the freezer. If I have opened a film canister or box of sheet film then it goes into a plastic bag and into the refrigerator. Both unexposed and exposed sheet film in the film holders go into individual bags and then into the frigerator.

Steve