diff --git a/edit.c b/edit.c
index 35fb763..9c76ef0 100644
--- a/edit.c
+++ b/edit.c
@@ -5,7 +5,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/edit.c,v 1.148 2008/12/13 17:02:12 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/edit.c,v 1.149 2008/12/29 21:05:13 tg Exp $");
 
 /* tty driver characters we are interested in */
 typedef struct {
@@ -49,10 +49,6 @@ static int x_vi(char *, size_t);
 #define x_flush()	shf_flush(shl_out)
 #define x_putc(c)	shf_putc((c), shl_out)
 
-#ifdef TIOCGWINSZ
-static void chkwinsz(void);
-#endif
-
 static int path_order_cmp(const void *aa, const void *bb);
 static char *add_glob(const char *, int);
 static void glob_table(const char *, XPtrV *, struct table *);
@@ -74,39 +70,10 @@ x_init(void)
 	    edchars.eof = -2;
 	/* default value for deficient systems */
 	edchars.werase = 027;	/* ^W */
-#ifdef TIOCGWINSZ
-	chkwinsz();
-#endif
+	change_winsz();
 	x_init_emacs();
 }
 
-#ifdef TIOCGWINSZ
-static void
-chkwinsz(void)
-{
-	struct winsize ws;
-
-	if (procpid == kshpid && ioctl(tty_fd, TIOCGWINSZ, &ws) >= 0) {
-		struct tbl *vp;
-
-		/* Do NOT export COLUMNS/LINES.  Many applications
-		 * check COLUMNS/LINES before checking ws.ws_col/row,
-		 * so if the app is started with C/L in the environ
-		 * and the window is then resized, the app won't
-		 * see the change cause the environ doesn't change.
-		 */
-		if (ws.ws_col) {
-			x_cols = ws.ws_col < MIN_COLS ? MIN_COLS : ws.ws_col;
-
-			if ((vp = typeset("COLUMNS", 0, 0, 0, 0)))
-				setint(vp, (long)ws.ws_col);
-		}
-		if (ws.ws_row && (vp = typeset("LINES", 0, 0, 0, 0)))
-			setint(vp, (long)ws.ws_row);
-	}
-}
-#endif
-
 /*
  * read an edited command line
  */
@@ -126,9 +93,7 @@ x_read(char *buf, size_t len)
 	else
 		i = -1;		/* internal error */
 	x_mode(false);
-#ifdef TIOCGWINSZ
-	chkwinsz();
-#endif
+	change_winsz();
 	return i;
 }
 
diff --git a/sh.h b/sh.h
index d4f77bc..08ce542 100644
--- a/sh.h
+++ b/sh.h
@@ -103,7 +103,7 @@
 #define __SCCSID(x)	__IDSTRING(sccsid,x)
 
 #ifdef EXTERN
-__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.270 2008/12/29 20:53:48 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/sh.h,v 1.271 2008/12/29 21:05:15 tg Exp $");
 #endif
 #define MKSH_VERSION "R36 2008/12/17"
 
@@ -685,7 +685,7 @@ EXTERN size_t	current_wd_size;
 #define MIN_COLS	(2 + MIN_EDIT_SPACE + 3)
 #define MIN_LINS	3
 EXTERN int x_cols I__(80);	/* tty columns */
-EXTERN int x_lins I__(24);	/* tty lines */
+EXTERN int x_lins I__(-1);	/* tty lines */
 
 /* These to avoid bracket matching problems */
 #define OPAREN	'('
@@ -1543,6 +1543,7 @@ char **makenv(void);
 #if !HAVE_ARC4RANDOM || !defined(MKSH_SMALL)
 void change_random(unsigned long);
 #endif
+void change_winsz(void);
 int array_ref_len(const char *);
 char *arrayname(const char *);
 void set_array(const char *, int, const char **);
diff --git a/var.c b/var.c
index 6099b2b..eb13c13 100644
--- a/var.c
+++ b/var.c
@@ -2,7 +2,7 @@
 
 #include "sh.h"
 
-__RCSID("$MirOS: src/bin/mksh/var.c,v 1.66 2008/12/29 20:52:10 tg Exp $");
+__RCSID("$MirOS: src/bin/mksh/var.c,v 1.67 2008/12/29 21:05:15 tg Exp $");
 
 /*
  * Variables
@@ -1291,3 +1291,37 @@ set_array(const char *var, int reset, const char **vals)
 		setstr(vq, vals[i], KSH_RETURN_ERROR);
 	}
 }
+
+void
+change_winsz(void)
+{
+	if (x_lins < 0) {
+		/* first time initialisation */
+#ifdef TIOCGWINSZ
+		if (tty_fd < 0)
+			/* non-FTALKING, try to get an fd anyway */
+			tty_init(false, false);
+#endif
+		x_cols = -1;
+	}
+
+#ifdef TIOCGWINSZ
+	/* check if window size has changed since first time */
+	if (tty_fd >= 0) {
+		struct winsize ws;
+
+		if (ioctl(tty_fd, TIOCGWINSZ, &ws) >= 0) {
+			if (ws.ws_col)
+				x_cols = ws.ws_col;
+			if (ws.ws_row)
+				x_lins = ws.ws_row;
+		}
+	}
+#endif
+
+	/* bounds check for sane values, use defaults otherwise */
+	if (x_cols < MIN_COLS)
+		x_cols = 80;
+	if (x_lins < MIN_LINS)
+		x_lins = 24;
+}