Abstract: Disclosed are compounds of the formula (I) and pharmaceutically acceptable salts thereof: (I) wherein Ring A, Ring B, Ring C, R1, R2, R3, R4, R5, L, m, n, and p are as defined herein. The compounds are modulators of G-protein coupled receptor 88 (GPR88). Also disclosed are pharmaceutical compositions comprising the compounds; and the compounds for use in the treatment of diseases mediated by GPR88, including Tourette's Syndrome, Huntington's Disease (HD), Addiction, Parkinson's Disease (PD), Schizophrenia, Alzheimer's disease, and Attention Deficit Hyperactivity Disorder (ADHD).