@@ -4,16 +4,16 @@
 import core.stdc.signal;
 
 class NilOutput : GameObserver
 {
-	this(const(Game) g) {}
-	override void on_game_changed(char c, const(Game) g, bool finished) {}
+	this(in Game g) {}
+	override void on_game_changed(char c, in Game g, bool finished) {}
 }
 
 class StdOutput : GameObserver
 {
-	this(const(Game) g) {}
-	override void on_game_changed(char c, const(Game) g, bool finished)
+	this(in Game g) {}
+	override void on_game_changed(char c, in Game g, bool finished)
 	{
 		stdout.write(c);
 		stdout.flush();
 	}
@@ -20,15 +20,15 @@
 }
 
 class GuardedOutput : GameObserver
 {
-	this(const(Game) g)
+	this(in Game g)
 	{
 		setup_sigint_handling();
 		ideal_log ~= g.score_if_abort_now;
 	}
 
-	override void on_game_changed(char c, const(Game) g, bool finished)
+	override void on_game_changed(char c, in Game g, bool finished)
 	{
 		log ~= c;
 		score_log ~= g.score;
 		ideal_log ~= g.score_if_abort_now;