diff --git a/src/index.js b/src/index.js
index b5f31ba..07ff761 100644
--- a/src/index.js
+++ b/src/index.js
@@ -440,14 +440,23 @@ class Board extends React.Component {
       return;
     }
     if (this.isHoldingPiece()) {
+      // Copy the board
+      var board = new Board();
+      board.state.squares = this.state.squares.slice();
+      board.state.squares[i] = board.state.squares[this.heldPiece()];
+      board.state.squares[this.heldPiece()] = null;
+
+      let moversKing = this.state.blackIsNext ?
+        new Piece(BLACK, KING) : new Piece(WHITE, KING);
+      if (board.inCheck(moversKing) != null) {
+        return;
+      }
       if (this.makeMove(this.heldPiece(), i) !== 0) {
         this.setHand({
             heldPiece: null,
         });
       }
-      return;
-    } 
-    if (this.state.squares[i] != null) {
+    } else if (this.state.squares[i] != null) {
       let isSquareBlack = isBlack(this.state.squares[i]);
       if(isSquareBlack === this.state.blackIsNext) {
         this.setHand({