diff --git a/css/chess.css b/css/chess.css
index 87c0956..65ff078 100644
--- a/css/chess.css
+++ b/css/chess.css
@@ -312,7 +312,12 @@ button:disabled .silhouette {
    user-select: none;
 }
 
-.cb-piece.cb-selected {
+.cb-piece.cb-in-check {
+   filter: drop-shadow(0 0 5px red);
+   -webkit-filter: drop-shadow(0 0 5px red);
+}
+
+.cb-piece.cb-selected, .cb-piece.cb-selected.cb-in-check {
    filter: drop-shadow(0 0 5px blue);
    -webkit-filter: drop-shadow(0 0 5px blue);
 }
diff --git a/js/pacosako_ui.js b/js/pacosako_ui.js
index 56d8175..8163b44 100644
--- a/js/pacosako_ui.js
+++ b/js/pacosako_ui.js
@@ -248,6 +248,7 @@ $(function (){
       $('#cb_board .cb-square').off('click.unselect');
       $('#cb_board .cb-square').off('click.destination');
       $('#cb_board .cb-piece.cb-selected').removeClass('cb-selected');
+      $('#cb_board .cb-piece.cb-in-check').removeClass('cb-in-check');
       $('#cb_board .cb-piece').removeAttr('style').appendTo('#cb_hidden');
       $('#cb_board .cb-start').removeClass('cb-start');
       $('#cb_board .cb-end').removeClass('cb-end');
@@ -335,6 +336,11 @@ $(function (){
          pieces.draggable('enable');
       }
 
+      if (game.isInCheck()) {
+         const clss = game.player === PS.LIGHT ? '.cb-lt-piece' : '.cb-dk-piece';
+         $('#cb_board ' + clss + '.cb-king').addClass('cb-in-check');
+      }
+
       let msg = '';
       let winner = game.winner;