A fourth and fifth series of the hit detective show have been planned, Moffat revealed last night (January 8) at a BAFTA screening of third series finale 'His Last Vow'.
"Benedict [Cumberbatch] and Martin [Freeman] are apparently in movies!" quipped the writer. "So we've got to schedule around them, but we'll get them made as quickly as we can."
Series producer Sue Vertue added: "We're working on it - it's dates."
Sherlock premiered its third series on BBC One on New Year's Day, following a two-year hiatus.
"We couldn't get together before then," said Vertue. "We did worry that [in] two years, you might forget about us, but clearly not!"
Moffat also suggested that the hiatus may have contributed to Sherlock's recent ratings success.
"Sherlock started very well, the second series did better than the first and now the third is doing better than the second," he said. "It shows the benefits of starvation - put things on less often!"
'His Last Vow' airs on BBC One on Sunday, January 12 at 8.30pm in the UK. The third series will debut on BBC America the following Sunday (January 19) in the US.
Sherlock: Complete Series Three and the Sherlock Series 1-3 Box Set are available to buy on DVD and Blu-ray from January 20.
Sherlock's Mark Gatiss, Steven Moffat delighted by 'Empty Hearse' ratings
Watch a trailer for Sherlock 'His Last Vow' below: