diff --git a/src/misc.h b/src/misc.h
index fe1143de..77b81d50 100644
--- a/src/misc.h
+++ b/src/misc.h
@@ -126,33 +126,6 @@ private:
 };
 
 
-/// sigmoid(t, x0, y0, C, P, Q) implements a sigmoid-like function using only integers,
-/// with the following properties:
-///
-///  -  sigmoid is centered in (x0, y0)
-///  -  sigmoid has amplitude [-P/Q , P/Q] instead of [-1 , +1]
-///  -  limit is (y0 - P/Q) when t tends to -infinity
-///  -  limit is (y0 + P/Q) when t tends to +infinity
-///  -  the slope can be adjusted using C > 0, smaller C giving a steeper sigmoid
-///  -  the slope of the sigmoid when t = x0 is P/(Q*C)
-///  -  sigmoid is increasing with t when P > 0 and Q > 0
-///  -  to get a decreasing sigmoid, change sign of P
-///  -  mean value of the sigmoid is y0
-///
-/// Use <https://www.desmos.com/calculator/jhh83sqq92> to draw the sigmoid
-
-inline int64_t sigmoid(int64_t t, int64_t x0,
-                                  int64_t y0,
-                                  int64_t  C,
-                                  int64_t  P,
-                                  int64_t  Q)
-{
-   assert(C > 0);
-   assert(Q != 0);
-   return y0 + P * (t-x0) / (Q * (std::abs(t-x0) + C)) ;
-}
-
-
 /// xorshift64star Pseudo-Random Number Generator
 /// This class is based on original code written and dedicated
 /// to the public domain by Sebastiano Vigna (2014).
diff --git a/src/search.cpp b/src/search.cpp
index c998f20d..0f524093 100644
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -309,9 +309,8 @@ void Thread::search() {
 
   complexityAverage.set(155, 1);
 
-  trend         = SCORE_ZERO;
-  optimism[ us] = Value(37);
-  optimism[~us] = -optimism[us];
+  trend = SCORE_ZERO;
+  optimism[us] = optimism[~us] = VALUE_ZERO;
 
   int searchAgainCounter = 0;
 
@@ -358,11 +357,11 @@ void Thread::search() {
               beta  = std::min(prev + delta, VALUE_INFINITE);
 
               // Adjust trend and optimism based on root move's previousScore
-              int tr = sigmoid(prev, 3, 10, 89, 116, 1);
+              int tr = 116 * prev / (std::abs(prev) + 89);
               trend = (us == WHITE ?  make_score(tr, tr / 2)
                                    : -make_score(tr, tr / 2));
 
-              int opt = sigmoid(prev, 7, 20, 169, 19350, 164);
+              int opt = 118 * prev / (std::abs(prev) + 169);
               optimism[ us] = Value(opt);
               optimism[~us] = -optimism[us];
           }