The present invention relates to a blocking mechanism for a parking lock of a shaft in a motor vehicle. The blocking mechanism includes a pawl pivotable about a pivot axis and which, in a blocked position, engages into at least one latch cut-out of a ratchet wheel connected to the shaft. The blocking mechanism includes an actuating mechanism having an actuating device for moving an actuation slider. The pawl is pivotable by a movement of the actuation slider. The actuation slider includes a first U-shaped component and a second U-shaped component which each have two side sections and a transverse section connecting the side sections. The first component and the second component are plugged into one another in opposite directions such that the transverse section of the one component at least partly closes the open end of the U shape of the component and vice versa.