diff --git a/ttt/game.py b/ttt/game.py
index 2f0e302..37536f1 100644
--- a/ttt/game.py
+++ b/ttt/game.py
@@ -58,4 +58,8 @@ class TTTGame:
 
     def check_winner(self, state, symbol):
         "Checks whether the player with `symbol` has won the game."
+        pattern_to_win = [[0, 1, 2], [3, 4, 5], [6, 7, 8], [0, 3, 6], [1, 4, 7], [2, 5, 8], [0, 4, 8], [2, 4, 6]]
+        for pattern in pattern_to_win:
+            if state["board"][pattern[0]]==symbol and state["board"][pattern[1]]==symbol and state["board"][pattern[2]]==symbol:
+                return True
         return False