A carburetor for an internal combustion engine in a power saw. The carburetor has at least one adjustment screw which is fastened and secured in a bore of a receiving part on the carburetor housing or on the internal combustion engine. A shim or clamping piece, which is secured against rotation, is arranged in a recess of the receiving part. The clamping piece receives the adjustment screw in a positive, locking manner. The clamping piece has projections with which the clamping piece is held locked in the recess of the receiving part.