As a supervisor at a logistics company, he had been instructed to never make use of machines to carry passengers.
But Malaysian Ngoi Chee Kin, 33, disobeyed the rules and transported a subordinate on his reach truck - with fatal consequences.
Ngoi, who used to be a material and freight handling supervisor at XPO Logistics Worldwide, was jailed for four weeks yesterday for causing material handler Teong Kok Wee's death while performing an act that endangered the safety of others.
He committed the offence at the company's Pandan Avenue warehouse on March 24, 2014.
At around 6.40pm that day, he asked Mr Teong, 28, and two co-workers to work overtime and retrieve some items that had to be delivered the next day.
Mr Teong, who was also a Malaysian, suggested that he stand on Ngoi's reach truck - which is similar to a forklift - to retrieve the items from some overhead racks.
Ministry of Manpower prosecutor Delvinder Singh said: "The accused agreed to this arrangement even though he knew he was not supposed to elevate any personnel using the reach truck."
Mr Teong then sat on the wooden pallets of the truck that Ngoi operated. They made their way to some racks and Ngoi elevated his colleague to a height of between 2m and 4m to retrieve the items. When the job was done, Ngoi retracted the mast of his truck and reversed it.
Mr Singh said: "As a result of the accused's act, the deceased fell backwards and off the wooden pallets, landing headfirst on the ground."
Mr Teong was taken to the National University Hospital, where he died of head injury five days later.
Ngoi's lawyer, Mr Steven Lam, asked District Judge Shaiffudin Saruwan to sentence his client to between two and three weeks' jail. He said that even though Ngoi was no longer working in Singapore, he had taken the trouble to return here to face the consequences of his actions.
Mr Singh asked the judge to jail him for four weeks, and stressed that as a supervisor, Ngoi should have exercised greater control over the situation. He added that instead of agreeing with Mr Teong's suggestion, he should have rejected it.
He said: "In the light of urgency, safety was compromised."
For performing an act that endangered the safety of others, Ngoi could have been jailed for up to two years and fined up to $200,000.