The present invention relates to novel compounds of formula (I) and methods for the manufacture of inhibitors of deubiquitylating enzymes (DUBs). In particular, the invention relates to the inhibition of ubiquitin C-terminal hydrolase 30 or ubiquitin specific peptidase 30 (USP30). The invention further relates to the use of DUB inhibitors in the treatment of conditions involving mitochondrial dysfunction and in the treatment of cancer.