Vodafone's share price may have reacted well to the company's third-quarter results on Thursday, but Nomura has highlighted concerns with the company's dividend on the back of accounting changes to be implemented next year.The telecoms group said that it will adopt new accounting changes next year (from April 1st 2013) which will have a "material impact" on a number of its key performance measures, including revenue, EBITDA and free cash flow (FCF). Specifically, FCF would have reduced by £0.4bn if the changes were applied in the year ended March 31st 2012.Nomura highlights that a similar adjustment would take next year's FCF to £4.4bn, compared with the current dividend outflow of £4.95bn."Vodafone's board will reconsider uses of cash flow following the expiry of its three-year dividend commitment, and we believe it may baulk at paying a dividend not covered by controlled cash flow. We reiterate our concerns for income investors and lack of certainty over the forward dividend is an overhang for the shares, in our view."As for the results, organic service revenues fell by 2.6% in the third quarter, 20 basis points worse than consensus estimates, Nomura said, with the UK and German "causing the most concern"."Although we think some of the decline can be attributed to a less aggressive customer investment in both European and emerging markets, we expect a deteriorating top line to bring further earnings pressure for the consolidated assets," the broker said.The broker has retained its 'neutral' rating and 195p target price for the stock.Shares were up 2.24% at 174.16p by 11:04 on Thursday.BC