diff --git a/src/util/Numerical.js b/src/util/Numerical.js
index b81718d8..42457699 100644
--- a/src/util/Numerical.js
+++ b/src/util/Numerical.js
@@ -356,8 +356,8 @@ var Numerical = new function() {
             }
             // The cubic has been deflated to a quadratic.
             var count = Numerical.solveQuadratic(a, b1, c2, roots, min, max);
-            if (isFinite(x) && count >= 0
-                    && (count === 0 || x !== roots[count - 1])
+            if (isFinite(x) && (count === 0
+                    || count > 0 && x !== roots[0] && x !== roots[1])
                     && (min == null || x > min - EPSILON && x < max + EPSILON))
                 roots[count++] = min == null ? x : clamp(x, min, max);
             return count;