diff --git a/app/src/main/java/com/acme/tictactoe/viewmodel/TicTacToeViewModel.java b/app/src/main/java/com/acme/tictactoe/viewmodel/TicTacToeViewModel.java
index d37b334..aa1ff5e 100644
--- a/app/src/main/java/com/acme/tictactoe/viewmodel/TicTacToeViewModel.java
+++ b/app/src/main/java/com/acme/tictactoe/viewmodel/TicTacToeViewModel.java
@@ -44,9 +44,12 @@ public void onResetSelected() {
     }
 
     public void onClickedCellAt(int row, int col) {
-        Player playerThatMoved = model.mark(row, col);
-        cells.put("" + row + col, playerThatMoved == null ? null : playerThatMoved.toString());
-        winner.set(model.getWinner() == null ? null : model.getWinner().toString());
+        if (!cells.containsKey("" + row + col)) {
+            Player playerThatMoved = model.mark(row, col);
+            cells.put("" + row + col, playerThatMoved == null ? null : playerThatMoved.toString());
+            winner.set(model.getWinner() == null ? null : model.getWinner().toString());
+        }
+
     }
 
 }