Carnival Cruise Line has cancelled the Dec. 5 and Dec. 11 sailings aboard the Carnival Horizon.

The company cited an issue with the ship affecting what it said was its maximum cruising speed, meaning Carnival could not operate these sailings, according to a letter sent to booked guests.

Guests will get a full refund and 100 percent future cruise credit based on the value of their cruise fare.

The Dec. 5 sailing was set to depart from Miami and call in Bimini and Half Moon Cay, as well as Amber Cove, with two days at sea.

The Dec. 11 sailing was a roundtrip cruise from Miami over eight nights with calls in Aruba, Curacao, La Romana, and Amber Cove.

The ship will now return to service for a week-long, seven-night cruise roundtrip from Miami to the Eastern Caribbean on Dec. 19.