diff --git a/usr.bin/top/screen.c b/usr.bin/top/screen.c
index 22608569d97..aeb9daf6d8c 100644
--- a/usr.bin/top/screen.c
+++ b/usr.bin/top/screen.c
@@ -36,6 +36,7 @@
 #  include <termios.h>
 # endif
 #endif
+#if defined(TERMIO) || defined(TERMIOS)
 # ifndef TAB3
 #  ifdef OXTABS
 #   define TAB3 OXTABS
@@ -43,6 +44,7 @@
 #   define TAB3 0
 #  endif
 # endif
+#endif
 #include <curses.h>
 #include <termcap.h>
 #include "screen.h"
@@ -73,12 +75,18 @@ char *end_standout;
 char *terminal_init;
 char *terminal_end;
 
+#ifdef SGTTY
 static struct sgttyb old_settings;
 static struct sgttyb new_settings;
+#endif
+#ifdef TERMIO
 static struct termio old_settings;
 static struct termio new_settings;
+#endif
+#ifdef TERMIOS
 static struct termios old_settings;
 static struct termios new_settings;
+#endif
 static char is_a_terminal = No;
 #ifdef TOStop
 static int old_lword;
@@ -209,18 +217,24 @@ int interactive;
     get_screensize();
 
     /* if stdout is not a terminal, pretend we are a dumb terminal */
+#ifdef SGTTY
     if (ioctl(STDOUT, TIOCGETP, &old_settings) == -1)
     {
 	smart_terminal = No;
     }
+#endif
+#ifdef TERMIO
     if (ioctl(STDOUT, TCGETA, &old_settings) == -1)
     {
 	smart_terminal = No;
     }
+#endif
+#ifdef TERMIOS
     if (tcgetattr(STDOUT, &old_settings) == -1)
     {
 	smart_terminal = No;
     }
+#endif
 }
 
 void
@@ -228,6 +242,7 @@ init_screen()
 
 {
     /* get the old settings for safe keeping */
+#ifdef SGTTY
     if (ioctl(STDOUT, TIOCGETP, &old_settings) != -1)
     {
 	/* copy the settings so we can modify them */
@@ -256,6 +271,8 @@ init_screen()
 	/* send the termcap initialization string */
 	putcap(terminal_init);
     }
+#endif
+#ifdef TERMIO
     if (ioctl(STDOUT, TCGETA, &old_settings) != -1)
     {
 	/* copy the settings so we can modify them */
@@ -278,6 +295,8 @@ init_screen()
 	/* send the termcap initialization string */
 	putcap(terminal_init);
     }
+#endif
+#ifdef TERMIOS
     if (tcgetattr(STDOUT, &old_settings) != -1)
     {
 	/* copy the settings so we can modify them */
@@ -300,6 +319,7 @@ init_screen()
 	/* send the termcap initialization string */
 	putcap(terminal_init);
     }
+#endif
 
     if (!is_a_terminal)
     {
@@ -324,12 +344,18 @@ end_screen()
     /* if we have settings to reset, then do so */
     if (is_a_terminal)
     {
+#ifdef SGTTY
 	(void) ioctl(STDOUT, TIOCSETP, &old_settings);
 #ifdef TOStop
 	(void) ioctl(STDOUT, TIOCLSET, &old_lword);
 #endif
+#endif
+#ifdef TERMIO
 	(void) ioctl(STDOUT, TCSETA, &old_settings);
+#endif
+#ifdef TERMIOS
 	(void) tcsetattr(STDOUT, TCSADRAIN, &old_settings);
+#endif
     }
 }
 
@@ -340,12 +366,18 @@ reinit_screen()
     /* install our settings if it is a terminal */
     if (is_a_terminal)
     {
+#ifdef SGTTY
 	(void) ioctl(STDOUT, TIOCSETP, &new_settings);
 #ifdef TOStop
 	(void) ioctl(STDOUT, TIOCLSET, &new_lword);
 #endif
+#endif
+#ifdef TERMIO
 	(void) ioctl(STDOUT, TCSETA, &new_settings);
+#endif
+#ifdef TERMIOS
 	(void) tcsetattr(STDOUT, TCSADRAIN, &new_settings);
+#endif
     }
 
     /* send init string */
@@ -360,6 +392,7 @@ get_screensize()
 
 {
 
+#ifdef TIOCGWINSZ
 
     struct winsize ws;
 
@@ -375,6 +408,25 @@ get_screensize()
 	}
     }
 
+#else
+#ifdef TIOCGSIZE
+
+    struct ttysize ts;
+
+    if (ioctl (1, TIOCGSIZE, &ts) != -1)
+    {
+	if (ts.ts_lines != 0)
+	{
+	    screen_length = ts.ts_lines;
+	}
+	if (ts.ts_cols != 0)
+	{
+	    screen_width = ts.ts_cols - 1;
+	}
+    }
+
+#endif /* TIOCGSIZE */
+#endif /* TIOCGWINSZ */
 
     (void) strncpy(lower_left, tgoto(cursor_motion, 0, screen_length - 1),
 	sizeof(lower_left) - 1);