A lid arrangement for a canister for a rollup truck bed cover comprises a lid and a canister. The canister has a main housing part and opposite housing end parts. The lid spans between said housing end parts across the main housing part, and the lid is pivotally connected to at least one of the housing end parts. The pivotal lid need not be taken fully off the canister when access is needed to the main housing part, e.g. to inspect the drain(s) or wipe up water inside the canister.