A 33-year-old man was taken to hospital after the truck he was driving collided with a semi trailer.
The man was driving along the Calder Freeway about 19 kilometres from Kyneton when the incident happened about 2.30pm.
Malmsbury police Leading Senior Constable Robert Sheridan said the driver of the smaller truck attempted to overtake the semi trailer but misjudged the distance.
He said the driver of the smaller truck ran into the rear of the semi trailer.
Leading Senior Constable Sheridan said the 53-year-old driver of the semi trailer was uninjured.
He said the driver of the smaller truck suffered head, leg and internal injuries but none were serious.
Traffic is being diverted around the accident.
State Emergency Service and Country Fire Authority personnel are on scene mopping up.