diff --git a/games/robots/flush_in.c b/games/robots/flush_in.c
index 894185c8597..18e270930b1 100644
--- a/games/robots/flush_in.c
+++ b/games/robots/flush_in.c
@@ -49,7 +49,7 @@ flush_in()
 {
 # ifdef TIOCFLUSH
 	ioctl(fileno(stdin), TIOCFLUSH, NULL);
-# else TIOCFLUSH
+# else /* TIOCFLUSH */
 	crmode();
-# endif TIOCFLUSH
+# endif /* TIOCFLUSH */
 }
diff --git a/games/robots/move_robs.c b/games/robots/move_robs.c
index 21bf0ba2150..23f39f6b778 100644
--- a/games/robots/move_robs.c
+++ b/games/robots/move_robs.c
@@ -62,7 +62,7 @@ bool	was_sig;
 	addch(inch());
 	move(Max.y, Max.x);
 	addch(inch());
-# endif DEBUG
+# endif /* DEBUG */
 	for (rp = Robots; rp < &Robots[MAXROBOTS]; rp++) {
 		if (rp->y < 0)
 			continue;
@@ -123,7 +123,7 @@ bool	was_sig;
 	move(Max.y, Max.x);
 	addch(inch());
 	standend();
-# endif DEBUG
+# endif /* DEBUG */
 	if (Real_time)
 		alarm(3);
 }
diff --git a/games/robots/play_level.c b/games/robots/play_level.c
index 6361d9b580a..b03bbc43487 100644
--- a/games/robots/play_level.c
+++ b/games/robots/play_level.c
@@ -67,7 +67,7 @@ play_level()
 	move(Max.y, Max.x);
 	addch(inch());
 	standend();
-# endif DEBUG
+# endif /* DEBUG */
 	setjmp(End_move);
 	flush_in();
 	while (!Dead && Num_robots > 0) {