Disclosed are compounds useful as inhibitors of the Wnt signalling pathway. Specifically, inhibitors of Porcupine (Porcn) are contemplated by the invention. In addition, the invention contemplates processes to prepare the compounds and uses of the compounds. The compounds of the invention may therefore be used in treating conditions mediated by the Wnt signalling pathway, for example, in treating cancer, sarcoma, melanoma, skin cancer, haematological tumors, lymphoma, carcinoma, and leukemia; or enhancing the effectiveness of an anti-cancer treatment.