diff --git a/src/board.h b/src/board.h
index 602bd4a..cb9ef80 100644
--- a/src/board.h
+++ b/src/board.h
@@ -36,7 +36,8 @@ typedef struct board_s {
 
 /* definitions for bitboard representation
  */
-#define BB(f, r)     (8 * (r) + (f))              /* from rank,file to bitboard */
+#define BB(f, r)     (1ULL << (8 * (r) + (f)))    /* from rank,file to bitboard */
+#define SQ88_2_BB(s) (BB(FILE88(s), RANK88(s)))   /* from sq88 to bitboard */
 #define FILEBB(b)    ((b) % 8)                    /* from sq88 to file */
 #define RANKBB(b)    ((b) / 8)                    /* from sq88 to rank */
 
diff --git a/src/fen.c b/src/fen.c
index 63390e6..3f814b7 100644
--- a/src/fen.c
+++ b/src/fen.c
@@ -83,7 +83,7 @@ pos_t *fen2pos(pos_t *pos, char *fen)
                 log_i(5, "f=%d r=%d *p=%c piece=%c color=%d\n",
                        file, rank, *p, cp, color);
 #               endif
-                pos->occupied[color] |= (1LL << BB(file, rank));
+                pos->occupied[color] |= BB(file, rank);
                 SET_COLOR(piece, color);
                 board[SQ88(file, rank)].piece = piece;
                 board[SQ88(file, rank)].s_piece =
diff --git a/src/move.c b/src/move.c
index 22aa9c0..920c84f 100644
--- a/src/move.c
+++ b/src/move.c
@@ -280,7 +280,7 @@ int pseudo_moves_pawn(pos_t *pos, piece_list_t *ppiece, bool doit)
 #       endif
         if (SQ88_NOK(new))
             continue;
-        pos->controlled[vcolor] |= (1ULL << BB(FILE88(new), RANK88(new)));
+        pos->controlled[vcolor] |= SQ88_2_BB(new);
         if (board[new].piece && COLOR(board[new].piece) != color) {
             //log_f(2, "pawn capture mobility\n");
             pos->mobility[vcolor]++;
@@ -374,6 +374,7 @@ int pseudo_moves_gen(pos_t *pos, piece_list_t *ppiece, bool doit)
     board_t *board = pos->board;
     move_t *move;
     int count = 0;
+    u64 bb_new;
 
 #   ifdef DEBUG_MOVE
     log_f(1, "pos:%p turn:%s piece:%d [%s %s] at %#04x[%c%c]\n",
@@ -397,22 +398,33 @@ int pseudo_moves_gen(pos_t *pos, piece_list_t *ppiece, bool doit)
 #               endif
                 break;
             }
+            bb_new = SQ88_2_BB(new);
 #           ifdef DEBUG_MOVE
-            log_i(4, "trying %c%c\n", FILE2C(GET_F(new)), RANK2C(GET_R(new)));
+            log_i(2, "trying %#x=%c%c bb=%#lx\n",
+                  new, FILE2C(GET_F(new)), RANK2C(GET_R(new)),
+                  bb_new);
+            //bitboard_print(new_bitboard);
 #           endif
 
-            pos->controlled[vcolor] |= (1ULL << BB(FILE88(new), RANK88(new)));
-            if (board[new].piece) {
+            pos->controlled[vcolor] |= bb_new;;
+
+            /* king: do not move to opponent controlled square */
+            if (piece == KING && pos->controlled[OPPONENT(vcolor)] & bb_new) {
 #               ifdef DEBUG_MOVE
-                log_i(5, "color=%d color2=%d\n", color, COLOR(board[new].piece));
+                log_i(1, "%s king cannot move to %c%c\n",
+                      IS_WHITE(color)? "white": "black",
+                      FILE2C(GET_F(new)), RANK2C(GET_R(new)));
+#               endif
+                break;
+            }
+
+            if (bb_new & pos->occupied[vcolor]) {
+                //bitboard_print(pos->occupied[vcolor]);
+                //bitboard_print(pos->occupied[OPPONENT(vcolor)]);
+#               ifdef DEBUG_MOVE
+                log_i(1, "BB: skipping %#llx [%c%c] (same color piece)\n",
+                      new, FILE2C(GET_F(new)), RANK2C(GET_R(new)));
 #               endif
-                /* own color on dest square */
-                if (COLOR(board[new].piece) == color) {
-#                   ifdef DEBUG_MOVE
-                    log_i(5, "skipping %04x (same color piece)\n", new);
-#                   endif
-                    break;
-                }
             }
 
             /* we are sure the move is valid : we create move */