diff --git a/slabtop.c b/slabtop.c
index 17c1fcca..16863fe2 100644
--- a/slabtop.c
+++ b/slabtop.c
@@ -414,7 +414,7 @@ int main(int argc, char *argv[])
 			tv.tv_sec = delay;
 			tv.tv_usec = 0;
 			if (select(STDOUT_FILENO, &readfds, NULL, NULL, &tv) > 0) {
-				if (read(0, &c, 1) != 1)
+				if (read(STDIN_FILENO, &c, 1) != 1)
 					break;
 				parse_input(c);
 			}
diff --git a/vmstat.c b/vmstat.c
index 9fca4ef4..809915a7 100644
--- a/vmstat.c
+++ b/vmstat.c
@@ -694,7 +694,7 @@ static int winhi(void)
 	struct winsize win;
 	int rows = 24;
 
-	if (ioctl(1, TIOCGWINSZ, &win) != -1 && win.ws_row > 0)
+	if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &win) != -1 && 0 < win.ws_row)
 		rows = win.ws_row;
 
 	return rows;
diff --git a/watch.c b/watch.c
index 6ce174ba..d759c64b 100644
--- a/watch.c
+++ b/watch.c
@@ -220,7 +220,7 @@ static void get_terminal_size(void)
 		}
 	}
 	if (incoming_cols < 0 || incoming_rows < 0) {
-		if (ioctl(2, TIOCGWINSZ, &w) == 0) {
+		if (ioctl(STDERR_FILENO, TIOCGWINSZ, &w) == 0) {
 			if (incoming_rows < 0 && w.ws_row > 0) {
 				height = w.ws_row;
 				snprintf(env_row_buf, sizeof env_row_buf,