diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 9abd9366..110b00a3 100644
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -59,10 +59,12 @@ Value Evaluation::value()
     case Phase::placing:
 #ifdef EVALUATE_MOBILITY
         if (gameOptions.getConsiderMobility()) {
-            value += (Value)pos.calculate_mobility_diff();
+            //value += (Value)pos.calculate_mobility_diff();
+            value += pos.get_mobility_diff();
         } else if (gameOptions.getDrawOnHumanExperience()) {
             if (pos.piece_on_board_count(WHITE) + pos.piece_on_board_count(BLACK) <= 5) {
-                value += (Value)pos.calculate_mobility_diff();
+                //value += (Value)pos.calculate_mobility_diff();
+                value += pos.get_mobility_diff();
             }
             //break;
         }
diff --git a/src/position.cpp b/src/position.cpp
index 1904e8cc..44691645 100644
--- a/src/position.cpp
+++ b/src/position.cpp
@@ -561,6 +561,8 @@ bool Position::reset()
     pieceInHandCount[WHITE] = pieceInHandCount[BLACK] = rule.piecesCount;
     pieceToRemoveCount = 0;
 
+    mobilityDiff = 0;
+
     MoveList<LEGAL>::create();
     create_mill_table();
     currentSquare = SQ_0;
@@ -633,6 +635,8 @@ bool Position::put_piece(Square s, bool updateRecord)
 
         update_key(s);
 
+        updateMobility(MOVETYPE_PLACE, s);
+
         if (updateRecord) {
             snprintf(record, RECORD_LEN_MAX, "(%1u,%1u)", file_of(s), rank_of(s));
         }
@@ -719,8 +723,12 @@ bool Position::put_piece(Square s, bool updateRecord)
         update_key(s);
         revert_key(currentSquare);
 
+        updateMobility(MOVETYPE_PLACE, s);
+
         board[currentSquare] = NO_PIECE;
 
+        updateMobility(MOVETYPE_REMOVE, currentSquare);
+
         CLEAR_BIT(byTypeBB[ALL_PIECES], currentSquare);
         CLEAR_BIT(byTypeBB[type_of(pc)], currentSquare);
         CLEAR_BIT(byColorBB[color_of(pc)], currentSquare);
@@ -730,6 +738,9 @@ bool Position::put_piece(Square s, bool updateRecord)
         SET_BIT(byColorBB[color_of(pc)], s);
 
         currentSquare = s;
+
+        
+
         const int n = mills_count(currentSquare);
 
         if (n == 0
@@ -781,6 +792,8 @@ bool Position::remove_piece(Square s, bool updateRecord)
 
     revert_key(s);
 
+    updateMobility(MOVETYPE_REMOVE, s);
+
     if (rule.hasBannedLocations && phase == Phase::placing) {
         // Remove and put ban
         Piece pc = board[s];
@@ -1341,6 +1354,53 @@ void Position::reset_bb()
     }
 }
 
+void Position::updateMobility(MoveType mt, Square s)
+{
+    if (mt == MOVETYPE_PLACE) {
+        for (MoveDirection d = MD_BEGIN; d < MD_NB; ++d) {
+            auto adjacentSquare = static_cast<Square>(MoveList<LEGAL>::adjacentSquares[s][d]);
+
+            if (!adjacentSquare) {
+                break;;
+            }
+            
+            if (board[adjacentSquare] & W_STONE) {
+                mobilityDiff--;
+            } else if (board[adjacentSquare] & B_STONE) {
+                mobilityDiff++;
+            } else {
+                if (side_to_move() == WHITE) {
+                    mobilityDiff++;
+                } else {
+                    mobilityDiff--;
+                }
+            }          
+        }
+    } else if (mt == MOVETYPE_REMOVE) {
+        for (MoveDirection d = MD_BEGIN; d < MD_NB; ++d) {
+            auto adjacentSquare = static_cast<Square>(MoveList<LEGAL>::adjacentSquares[s][d]);
+
+            if (!adjacentSquare) {
+                break;
+            }
+
+            if (board[adjacentSquare] & W_STONE) {
+                mobilityDiff++;
+            } else if (board[adjacentSquare] & B_STONE) {
+                mobilityDiff--;
+            } else {
+                if (side_to_move() == WHITE) {
+                    mobilityDiff++;
+                } else {
+                    mobilityDiff--;
+                }
+            } 
+        }
+    } else {
+        assert(0);
+    }
+}
+
 void Position::mirror(vector <string> &moveHistory, bool cmdChange /*= true*/)
 {
     Piece ch;
diff --git a/src/position.h b/src/position.h
index 04245d3f..eeff374a 100644
--- a/src/position.h
+++ b/src/position.h
@@ -145,6 +145,10 @@ public:
 
     int piece_to_remove_count() const;
 
+    int get_mobility(Color c) const;
+    int get_mobility_diff() const;
+    void updateMobility(MoveType mt, Square s);
+    //template <typename Mt> void updateMobility(Square from, Square to);
     int calculate_mobility_diff();
 
     static bool is_star_square(Square s);
@@ -172,6 +176,7 @@ public:
     int pieceInHandCount[COLOR_NB] { 0, 9, 9 };
     int pieceOnBoardCount[COLOR_NB] { 0, 0, 0 };
     int pieceToRemoveCount{ 0 };
+    int mobilityDiff { 0 };
     int gamePly { 0 };
     Color sideToMove { NOCOLOR };
     Thread *thisThread {nullptr};
@@ -344,4 +349,9 @@ inline int Position::piece_to_remove_count() const
     return pieceToRemoveCount;
 }
 
+inline int Position::get_mobility_diff() const
+{
+    return mobilityDiff;
+}
+
 #endif // #ifndef POSITION_H_INCLUDED