In the paper we study the uniqueness of entire functions sharing a small function with their derivatives. The results of the paper improve the corresponding results of Jank, Mues and Volkman (Complex Variables Theory Appl. 6, 1 (1986), 51--71), Zhong (Kodai Math. J. 18, 2 (1995), 250--259) and Lahiri-Ghosh (Analysis (Munich) 31, 1 (2011), 47--59).