In this paper we apply a novel non-uniform slant correc- tion preprocessing technique to improve the recognition of offline handwritten text lines. The local slant correction is expressed as a global optimisation problem of the sequence of local slant angles. This is different to conventional slant removal techniques that rely on the average slant angle. Ex- periments based on a state-of-the-art handwritten text line recogniser show a significant gain in word level accuracy for the investigated preprocessing methods.