Changes may have to be made to legislation that would give Victorians the right to an assisted death, after an MP in the upper house said he would only support the bill if there were two amendments.

Independent MP James Purcell will demand that any person seeking an assisted death must be medically assessed as within six months of dying, not 12.

The western Victorian upper house MP also wants a role for the patient's GP, arguing that a decision on whether someone is mentally fit to request an assisted death, and is under no pressure from family members, should not be left to doctors who do not know them.

The Andrews government's voluntary assisted dying bill passed the lower house without amendments this month after a gruelling session in Parliament that lasted more than 24 hours.