Syntheses along the Tl₅(As,Sb)₁₃S₂₂ compositional line in the Tl₂S-As₂S₃-Sb₂S₃ phase system showed that the compositional range of rebulite extends from Tl₅As_9.5Sb_3.5S₂₂ to Tl₅As_7.75Sb_5.25S₂₂. The Sb-rich end-member is in equilibrium with jankovićite of the ideal composition Tl₅Sb_7.5As_5.5S₂₂, which is considered to be the As-rich end-member of the jankovićite solid solution. The crystal structure analysis of specimens from the As and Sb end-members of rebulite show that the Sb/As substitution is present in Sb3, Sb4, Sb5, As1 and As2 structural sites. Of them, Sb3 is always Sb dominated whereas other four vary from As- to Sb-dominated over the range of the solid solution. The change of the structural topology from jankovićite to rebulite, closely related but not identical structures, is explained through the necessity to accommodate the smaller volumes of the As coordination polyhedra, and is accomplished through unit-cell twinning over the periodic (001)_reb twin boundaries. The As end-member of the rebulite solid solution is in equilibrium with a phase of composition close to Tl_2.4Sb_0.68As_7.18S₁₃, interpreted as imhofite.