diff --git a/src/attack.c b/src/attack.c
index b56db1c..9c2e003 100644
--- a/src/attack.c
+++ b/src/attack.c
@@ -20,6 +20,9 @@
 #include "hyperbola-quintessence.h"
 #include "attack.h"
 
+
+// #define DEBUG_ATTACK_ATTACKERS1
+
 /**
  * sq_attackers() - find attackers on a square
  * @pos: position
@@ -36,9 +39,6 @@
  *
  * @Return: a bitboard of attackers.
  */
-
-// #define DEBUG_ATTACK_ATTACKERS1
-
 bitboard_t sq_attackers(const pos_t *pos, const square_t sq, const color_t c)
 {
     bitboard_t attackers = 0, tmp;
@@ -96,24 +96,24 @@ bitboard_t sq_attackers(const pos_t *pos, const square_t sq, const color_t c)
 }
 
 /**
- * sq_pinners() - find pinners on a square
+ * sq_pinners() - get "pinners" on a square
  * @pos: position
  * @sq:  square to test
- * @c:   attacker color
+ * @color:   attacker color
  *
  * Find all @c pieces which are separated from @sq by only one piece (of
  * any color).
  *
- * @Return: a bitboard of attackers.
+ * @Return: bitboard of pinners.
  */
-bitboard_t sq_pinners(const pos_t *pos, const square_t sq, const color_t c)
+bitboard_t sq_pinners(const pos_t *pos, const square_t sq, const color_t color)
 {
     bitboard_t attackers, pinners = 0;
     bitboard_t occ = pos_occ(pos);
     bitboard_t maybe_pinner, tmp, lines;
 
     /* bishop type */
-    attackers = pos->bb[c][BISHOP] | pos->bb[c][QUEEN];
+    attackers = pos->bb[color][BISHOP] | pos->bb[color][QUEEN];
     /* occupancy on sq diag and antidiag */
     lines = (bb_sqdiag[sq] | bb_sqanti[sq]) & occ;
     bit_for_each64(maybe_pinner, tmp, attackers) {
@@ -124,7 +124,7 @@ bitboard_t sq_pinners(const pos_t *pos, const square_t sq, const color_t c)
     }
 
     /* same for rook type */
-    attackers = pos->bb[c][ROOK] | pos->bb[c][QUEEN];
+    attackers = pos->bb[color][ROOK] | pos->bb[color][QUEEN];
     lines = (bb_sqrank[sq] | bb_sqfile[sq]) & occ;
     bit_for_each64(maybe_pinner, tmp, attackers) {
         bitboard_t between = bb_between_excl[maybe_pinner][sq];
diff --git a/src/fen.c b/src/fen.c
index 1abf318..de9fbaf 100644
--- a/src/fen.c
+++ b/src/fen.c
@@ -133,7 +133,8 @@ static int fen_check(pos_t *pos)
     if (!(error = pos_check(pos, 0))) {
         /* TODO: Should it really be here ? */
         pos->checkers = pos_checkers(pos, pos->turn);
-        pos->pinners  = pos_pinners(pos, pos->turn);
+        pos->pinners = pos_king_pinners(pos, pos->turn);
+        pos->blockers = pos_king_blockers(pos, pos->turn, pos->pinners);
     }
     return error ? -1: warning;
 }
diff --git a/src/position.c b/src/position.c
index eba638f..d33b7ad 100644
--- a/src/position.c
+++ b/src/position.c
@@ -132,18 +132,46 @@ bitboard_t pos_checkers(const pos_t *pos, const color_t color)
 }
 
 /**
- * pos_pinners() - find all pinners on a king.
+ * pos_king_pinners() - get the "pinners" on a king "pinners".
  * @pos:   &position
- * @color: king color
+ * @color: king color.
  *
- * Get a bitboard of all pinners on @color king.
- * Just a wrapper over @sq_pinners().
+ * get position "pinners" on @color king. Here, pinner means a piece separated from king
+ * by one piece (any color) only.
+ * This is just a wrapper over @sq_pinners().
  *
- * @return: a bitboard of pinners.
+ * @return: pinners bitboard.
  */
-bitboard_t pos_pinners(const pos_t *pos, const color_t color)
+bitboard_t pos_king_pinners(const pos_t *pos, const color_t color)
 {
-    return sq_pinners(pos, pos->king[color], OPPONENT(color));
+    return sq_pinners(pos, pos->king[color], OPPONENT(pos->turn));
+}
+
+/**
+ * pos_king_blockers() - get the pin blockers on a king.
+ * @pos:   &position
+ * @color: king color.
+ * @pinners: pinners bitboard.
+ *
+ * get @pinners blockers pieces on @color king.
+ *
+ * @return: blockers bitboard.
+ */
+bitboard_t pos_king_blockers(const pos_t *pos, const color_t color, const bitboard_t pinners)
+{
+    bitboard_t tmp, blockers = 0, occ = pos_occ(pos);
+    square_t pinner, king = pos->king[color];
+
+    bit_for_each64(pinner, tmp, pinners) {
+        bitboard_t blocker = bb_between_excl[pinner][king] & occ;
+        warn_on(popcount64(blocker) != 1);
+        if (popcount64(blocker) != 1) {
+            printf("n blockers = %d\n", popcount64(blocker));
+            bb_print("blockers", blocker);
+        }
+        blockers |= blocker;
+    }
+    return blockers;
 }
 
 /**
@@ -233,6 +261,7 @@ void pos_print(const pos_t *pos)
     printf("fen %s\n", pos2fen(pos, str));
     printf("checkers: %s\n", pos_checkers2str(pos, str, sizeof(str)));
     printf("pinners : %s\n", pos_pinners2str(pos, str, sizeof(str)));
+    printf("blockers: %s\n", pos_blockers2str(pos, str, sizeof(str)));
 }
 
 /**
diff --git a/src/position.h b/src/position.h
index cb15ec5..1cb2390 100644
--- a/src/position.h
+++ b/src/position.h
@@ -39,10 +39,13 @@ typedef struct __pos_s {
     bitboard_t controlled[2];                     /* unsure */
     bitboard_t checkers;                          /* opponent checkers */
     bitboard_t pinners;                           /* opponent pinners */
+    bitboard_t blockers;                          /* pieces blocking pin */
     piece_t board[BOARDSIZE];
     movelist_t moves;
 } pos_t;
 
+#define pos_pinned(p)                  (p->blockers & p->bb[p->turn][ALL_PIECES])
+
 /**
  * pos_set_sq - unconditionally set a piece on a square
  * @pos: position
@@ -120,7 +123,7 @@ static __always_inline int pos_between_count(const pos_t *pos,
 
 /**
  * pos_checkers2str() - get of string of checkers.
- * @pos:   position
+ * @p:   position
  * @str:   destination string
  * @len:   max @str len.
  *
@@ -128,8 +131,9 @@ static __always_inline int pos_between_count(const pos_t *pos,
  *
  * @return: @str.
  */
-#define pos_checkers2str(pos, str, len)  bb_sq2str((pos)->checkers, (str), (len))
-#define pos_pinners2str(pos, str, len)   bb_sq2str((pos)->pinners, (str), (len))
+#define pos_checkers2str(p, str, len)  bb_sq2str(p->checkers, str, len)
+#define pos_pinners2str(p, str, len)   bb_sq2str(p->pinners, str, len)
+#define pos_blockers2str(p, str, len)  bb_sq2str(p->blockers, str, len)
 
 //void bitboard_print(bitboard_t bb, char *title);
 //void bitboard_print2(bitboard_t bb1, bitboard_t bb2, char *title);
@@ -140,7 +144,9 @@ extern void pos_del(pos_t *pos);
 extern pos_t *pos_clear(pos_t *pos);
 
 extern bitboard_t pos_checkers(const pos_t *pos, const color_t color);
-extern bitboard_t pos_pinners(const pos_t *pos, const color_t color);
+extern bitboard_t pos_king_pinners(const pos_t *pos, const color_t color);
+extern bitboard_t pos_king_blockers(const pos_t *pos, const color_t color, const bitboard_t );
+//extern bitboard_t set_king_pinners_blockers(pos_t *pos);
 //extern char *pos_checkers2str(const pos_t *pos, char *str);
 //extern char *pos_pinners2str(const pos_t *pos, char *str);