diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 8a21b0bb5b2..7ecc06aa0f1 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -101,7 +101,7 @@ namespace {
 
   // MobilityBonus[PieceType-2][attacked] contains bonuses for middle and end game,
   // indexed by piece type and number of attacked squares in the mobility area.
-  constexpr Score MobilityBonus[][32] = {
+  Score MobilityBonus[][32] = {
     { S(-62,-81), S(-53,-56), S(-12,-30), S( -4,-14), S(  3,  8), S( 13, 15), // Knights
       S( 22, 23), S( 28, 27), S( 33, 33) },
     { S(-48,-59), S(-20,-23), S( 16, -3), S( 26, 13), S( 38, 24), S( 51, 42), // Bishops
@@ -117,6 +117,8 @@ namespace {
       S(106,184), S(109,191), S(113,206), S(116,212) }
   };
 
+  TUNE(SetRange(-150, 150), MobilityBonus[KNIGHT - 2]);
+
   // Outpost[knight/bishop][supported by pawn] contains bonuses for minor
   // pieces if they occupy or can reach an outpost square, bigger if that
   // square is supported by a pawn.
diff --git a/src/psqt.cpp b/src/psqt.cpp
index 934f98986c2..bc6cbfb4e06 100644
--- a/src/psqt.cpp
+++ b/src/psqt.cpp
@@ -35,7 +35,7 @@ namespace PSQT {
 // type on a given square a (middlegame, endgame) score pair is assigned. Table
 // is defined for files A..D and white side: it is symmetric for black side and
 // second half of the files.
-constexpr Score Bonus[][RANK_NB][int(FILE_NB) / 2] = {
+Score Bonus[][RANK_NB][int(FILE_NB) / 2] = {
   { },
   { // Pawn
    { S(  0, 0), S(  0,  0), S(  0, 0), S( 0, 0) },
@@ -123,4 +123,6 @@ void init() {
   }
 }
 
+TUNE(SetRange(-250, 250), Bonus[KNIGHT], init);
+
 } // namespace PSQT