diff --git a/libcockatrice_network/libcockatrice/network/server/remote/server_player_reference.h b/libcockatrice_network/libcockatrice/network/server/remote/server_player_reference.h
index 07b2d3d2b..b478a4244 100644
--- a/libcockatrice_network/libcockatrice/network/server/remote/server_player_reference.h
+++ b/libcockatrice_network/libcockatrice/network/server/remote/server_player_reference.h
@@ -24,7 +24,7 @@ public:
     {
         return playerId;
     }
-    bool operator==(const PlayerReference &other)
+    bool operator==(const PlayerReference &other) const
     {
         return ((roomId == other.roomId) && (gameId == other.gameId) && (playerId == other.playerId));
     }