diff --git a/glicko2/glicko2.py b/glicko2/glicko2.py
index 08567dd..78f61fd 100644
--- a/glicko2/glicko2.py
+++ b/glicko2/glicko2.py
@@ -121,7 +121,7 @@ def _newVol(self, rating_list, RD_list, outcome_list, v):
           C = A + ((A - B) * fA)/(fB - fA)
           fC = self._f(C, delta, v, a)
           #b
-          if fC * fB < 0:
+          if fC * fB <= 0:
             A = B
             fA = fB
           else: