A wind turbine blade is provided, including two planks joined with each other in a longitudinal direction of the planks at joining surfaces by a butt joint, wherein each plank includes a main portion with a wedge-shaped recess and a wedge-shaped portion filling the recess, each wedge-shaped portion has a respective one of the joining surfaces and is tapered from its joining surface in a direction away from its joining surface, and a stiffness of a material of the wedge-shaped portions is smaller than a stiffness of a material of the main portions. By having the wedge-shaped portions, the load is transferred to the surrounding material over a larger area which reduces the stress concentration.