diff --git a/src/main.cpp b/src/main.cpp
index b516eac..ded6623 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -20,30 +20,30 @@ struct game_state {
 	char board[TILE_COUNT];
 };
 
-int check_win_condition(game_state * gs, char player) {
+int check_win_condition(const game_state& gs, char player) {
 	int i;
 	for( i = 0 ; i < 3 ; i++){
 		//rows
-		if(gs->board[(i*3)]==player && gs->board[(i*3)+1]==player && gs->board[(i*3)+2]==player)
+		if(gs.board[(i*3)]==player && gs.board[(i*3)+1]==player && gs.board[(i*3)+2]==player)
 			return 1;
 		//column
-		if(gs->board[i]==player && gs->board[i+3]==player && gs->board[i+6]==player)
+		if(gs.board[i]==player && gs.board[i+3]==player && gs.board[i+6]==player)
 			return 1;
 	}
-	if(gs->board[0] == player && gs->board[4] == player && gs->board[8] == player)
+	if(gs.board[0] == player && gs.board[4] == player && gs.board[8] == player)
 		return 1;
-	if(gs->board[2] == player && gs->board[4] == player && gs->board[6] == player)
+	if(gs.board[2] == player && gs.board[4] == player && gs.board[6] == player)
 		return 1;
 
 	return 0;
 }
 
-void display_game_state(game_state * gs){
-	printf("turn %i:\n",gs->turn);
+void display_game_state(const game_state& gs){
+	printf("turn %i:\n", gs.turn);
 	for(int i = 0; i < 3; i++){
 		for(int j = 0; j < 3 ; j++){
-			if(gs->board[(i*3)+j])
-				printf("%c", gs->board[(i*3)+j]);
+			if(gs.board[(i*3)+j])
+				printf("%c", gs.board[(i*3)+j]);
 			else
 				printf("_");
 		}
@@ -51,40 +51,40 @@ void display_game_state(game_state * gs){
 	}
 }
 
-void player_turn(game_state * gs, char player, int input)
+void player_turn(game_state& gs, char player, int input)
 {
 	if(input > TILE_COUNT && input < 0)
 		fprintf(stderr,"ERR: player input not in range.");
-	if(!gs->board[input])
-		gs->board[input] = player;
-	if(check_win_condition(gs,player)){
+	if(!gs.board[input])
+		gs.board[input] = player;
+	if(check_win_condition(gs, player)){
 		printf("player %c wins!\n", player);
-		gs->turn = -1;
+		gs.turn = -1;
 	}
 }
 
-void game_turn(game_state * gs,int player_input){
-	gs->turn++;
+void game_turn(game_state& gs,int player_input){
+	gs.turn++;
 	player_turn(gs, 'O', player_input);
 	display_game_state(gs);
-	if(gs->turn == -1)
+	if(gs.turn == -1)
 		return;
 	player_turn(gs, 'X', rand()%TILE_COUNT);
 	display_game_state(gs);
 }
 
-int exists_empty_tile(game_state * gs){
+int exists_empty_tile(const game_state& gs){
 	int i;
 	for( i = 0; i < TILE_COUNT ; i++)
-		if(!gs->board[i])
+		if(!gs.board[i])
 			return 1;
 	return 0;
 }
 
 int main(){
 	srand(time(NULL));
-	game_state gs = {0,0};
-	while(exists_empty_tile(&gs) && gs.turn != -1){
-		game_turn(&gs, get_player_input());
+	game_state gs = {};
+	while(exists_empty_tile(gs) && gs.turn != -1){
+		game_turn(gs, get_player_input());
 	}
 }