Experiments at JET designed to study the screening of wall sources of hydrocarbons showed that it was possible to raise the electron density in the periphery of the Scrape-Off Layer (SOL) without affecting the separatrix density. This observation led to the proposal that CD4 injection might be used to improve the coupling for Lower Hybrid heating and Current Drive (LHCD) in Optimised Shear (OS) discharges. Low peripheral SOL density occurs when type III ELMs appear, leading to poor LHCD coupling. CD4 puffing has now been used in OS discharges and typical results show that the reflected power is dropped from 8% to 4% with less fluctuation in coupled power. No adverse effect on the pedestal or bulk plasma profiles is observed.