A salesman who was originally fined a total of $12,500 and banned from driving for causing death and drink driving will now have to go to jail.

Justice Chan Seng Onn allowed the prosecution's appeal on Friday and imposed a four-month jail sentence on Wong Yew Foo, 39.

Wong was also banned from driving for six years - up by two years.

He had pleaded guilty to causing the death of Mr Sin San Wah, 67, through his negligence along Jalan Bukit Merah at about 9.30pm on April 4 last year as well as drink driving.

The lower court had fined him $10,000 for the fatal accident and $2,500 for drink driving. He was also banned from driving for four years.

Wong and his friends had earlier ordered six bottles of beer at a coffeeshop in Geylang when they met for dinner. He consumed two bottles.

He took a friend home in his car and was on his way home when the accident occurred.

While he was at the slip road from Lower Delta Road to Jalan Bukit Merah, he failed to stop at the stop line, and ploughed into the retiree who was cycling on the left side of the road.

The cyclist was found pinned under Wong's car which stopped in the middle of the road 4.5m away.

Wong was given two weeks to settle his affairs before commencing his jail term on July 12.