On Tuesday, the online retailer notified its third-party merchants that they would be able to use FedEx Ground to ship orders again.

About a month ago, orders that were placed under the Amazon Prime membership program were not performing well; packages were missing their on-time marks for Prime orders that are generally guaranteed to arrive within a day or two. FedEx was also missing many delivery windows, which led to many customers complaining to Amazon. As a result, Amazon imposed a ban; merchants were not allowed to utilize FedEx Ground to send out their goods.

An Amazon spokesman said FedEx Ground has been reinstated for Prime shipments fulfilled by third-party sellers because services have gone back to meeting the retailer’s on-time delivery requirements.

However, there was a delay in reinstating the utilization of FedEx Ground; Amazon had been tracking FedEx’s performance over seven days and the shipping service experienced some disruptions at the beginning of January, which is typically a busy time for returns. That is why the ban was not lifted shortly after peak shipping season ended.

Amazon and FedEx also cut business ties last year when they allowed two shipping contracts totaling some $900 million in revenue for FedEx expire. This meant that Amazon could no longer use FedEx for products shipped directly, but that third-party sellers could still ship with the service.