West Ham United have been fined £30,000 by the Football Association after admitting to a whereabouts breach of anti-doping regulations.
The club accepted a charge after three whereabouts violations in one year, saying the errors were administrative in nature.
Under the FA's rules, there must be a daily time window when players are available for testing by anti-doping control officers.
"The club accepts the charge and we will endeavour to tighten our procedures to avoid this happening again," a West Ham spokesperson said. "The breach related to administrative oversights on The FA's whereabouts system, where, for example, a player's address had been registered and the house number digits transposed.
"We would like to reiterate that the breach was a club administrative matter and did not concern any of our players."
Meanwhile, West Ham defender Winston Reid is expected to miss the rest of the season with a knee injury.
The absence of the 29-year-old New Zealander would be a major blow to West Ham's bid to stay in the Premier League.
Reid played for the first time in almost two months at Swansea City on Saturday but was replaced by right-back Sam Byram after 27 minutes.
Byram could also miss the rest of the campaign with an ankle problem.