The invention provides a stabilized fuel additive composition comprising a major portion of the reaction product of a 4-alkyl-2-morpholinone and an alkylphenoxypolyoxyalkylene amine and a minor portion of a stabilizing agent sufficient to prevent the formation of haze in the additive composition comprising a compound selected from polypropyleneoxide diamines of formula H.sub.2 N(CH.sub.2 CHCH.sub.3 O).sub.n NH.sub.2 where n is a number between about 4 and about 25, and triethylene tetramine. A method of stabilizing a fuel additive composition is also provided.