diff --git a/src/game.clj b/src/game.clj
index 5d21e82..98a4187 100644
--- a/src/game.clj
+++ b/src/game.clj
@@ -7,7 +7,7 @@
   (get-in state [:games game]))
 
 (defn add-player-of-game [state game player]
-  (update-in state [:games game] #(conj % player)))
+  (update-in state [:games game] #(set (conj % player))))
 
 (defn remove-player-of-game [state game player]
   (update-in state [:games game] #(disj % player)))