In the title salt, C(20)H(24)FN(2)O(2) (+)·0.5C(4)H(2)O(4) (2-), the fumarate anion is located on an inversion centre. In the cation, the two benzene rings are nearly perpendicular to each other, making a dihedral angle of 87.41 (10)°. The cation is linked to the anion by a bifurcated N-H⋯O hydrogen bond. Classical O-H⋯O and weak C-H⋯F hydrogen bonding is also present in the crystal structure. Three C atoms of the N,N-dimethyl-butanaminium moiety are disordered over two sites with refined site occupancies of 0.466 (14) and 0.534 (14).