An energy converting machine includes a guide vane. The guide vane includes a guide vane body for guiding a streaming fluid. The guide vane body has a pressure surface and a suction surface, a trailing edge and a leading edge, and a winglet for reducing leakage of the streaming fluid from the pressure surface to the suction surface. The winglet is arranged at a longitudinal end of the guide vane body. The winglet extents from the trailing edge to the leading edge and is arranged at the pressure surface. The winglet is free of protrusions beyond the leading edge and beyond the trailing edge.