diff --git a/src/OptAlgorithm/OptTimeCalculator.py b/src/OptAlgorithm/OptTimeCalculator.py
index 2630f4f..df6bd67 100644
--- a/src/OptAlgorithm/OptTimeCalculator.py
+++ b/src/OptAlgorithm/OptTimeCalculator.py
@@ -176,7 +176,7 @@ class OptTimeCalculator(AutoConfigClass):
         t5max = (Tfull - v0 / a) / 2 - t1
         v1 = v0 + a * t1
         S1 = v0 * t1 + a * t1 * t1 / 2 + v1 * t31 - a * t31 * t31 / 2
-        S2max = Sfull + S1
+        S2max = -Sfull + S1
         t5 = min(t5max, (vmax) / a, sqrt(S2max / a))
         t3 = abs(v0) / a + t1 + t5
         t32 = t5