1 files changed, 7 insertions, 3 deletions
diff --git a/src/engine/ttable.c b/src/engine/ttable.c
index fc1b6f0..c98bf62 100644
--- a/src/engine/ttable.c
+++ b/src/engine/ttable.c
@@ -23,9 +23,13 @@ void zobrist_init() {
 
 u64 zobrist_hash(position_t position) {
   u64 output = 0;
-  for (int i = 0; i < 64; i++) {
-    int piece_type = find_piece_on_square(&position, i);
-    output ^= zobrist_keys.piece[piece_type][i];
+  for (int piece = 0; piece < PIECE_TYPE_COUNT; piece++) {
+    bitboard_t bb = position.bitboards[piece];
+    while (bb) {
+      int sq = __builtin_ctzll(bb);
+      bb &= bb - 1;
+      output ^= zobrist_keys.piece[piece][sq];
+    }
   }
 
   if (position.castling & WHITE_SHORT_CASTLE) {