Pub group JD Wetherspoon has warned its annual profits may miss forecasts because of the costs of preparing its pubs for the smoking ban in England.
From July, drinkers in England will have to go outside for a sly smoke
Earlier bans in Wales and Scotland had a similar effect, the group said.
Wetherspoon's said it had been carrying out more repairs to its pubs ahead of the English ban in July.
The firm added it had also increased the size of non-smoking areas in its pubs which had boosted food sales, although bar volumes were down.
Wetherspoon's warning came as the Watford-based company reported an increase in three- and six-month sales.
"Typical Wetherspoon, can't resist the downbeat finish to a relatively upbeat statement," said Mark Brumby, an analyst at Blue Oar Securities.
The company's shares fell 5.6% to 670 pence in trading in London.