  The interplay of mesonic fluctuations with an axial $U(1)_A$-symmetry
breaking and resulting effects on the location of a possibly existing critical
endpoint in the QCD phase diagram are investigated in a framework of the
functional renormalization group within a $N_f = 2 + 1$ flavor quark-meson
model truncation. The axial $U(1)_A$-symmetry breaking is imposed by a mesonic
Kobayashi-Maskawa-'t Hooft determinant. The quark mass sensitivity of the
chiral phase transition with and without the $U(1)_A$-symmetry breaking is
studied.
