diff -uNr ../ncurses2/ncurses-5.4/ncurses/tty/tty_update.c ncurses-5.4/ncurses/tty/tty_update.c
--- ../ncurses2/ncurses-5.4/ncurses/tty/tty_update.c	2004-12-04 02:58:51.000000000 +0900
+++ ncurses-5.4/ncurses/tty/tty_update.c	2004-12-04 03:01:54.000000000 +0900
@@ -1182,7 +1182,9 @@
 		firstChar = nFirstChar;
 		/* find the first differing character */
 		while (firstChar < screen_columns
-		       && CharEq(newLine[firstChar], oldLine[firstChar]))
+		       && (CharEq(newLine[firstChar], oldLine[firstChar])
+			   || (isnac(newLine[firstChar])
+			       && isnac(oldLine[firstChar]))))
 		    firstChar++;
 	    } else if (oFirstChar > nFirstChar) {
 		firstChar = nFirstChar;
@@ -1209,7 +1211,9 @@
 	} else {
 	    /* find the first differing character */
 	    while (firstChar < screen_columns
-		   && CharEq(newLine[firstChar], oldLine[firstChar]))
+		   && (CharEq(newLine[firstChar], oldLine[firstChar])
+		       || (isnac(newLine[firstChar])
+			   && isnac(oldLine[firstChar]))))
 		firstChar++;
 	}
 	/* if there wasn't one, we're done */
@@ -1294,6 +1298,12 @@
 		    > (m - n)) {
 		    PutRange(oldLine, newLine, lineno, n + 1, m);
 		} else {
+		    if (isnac(newLine[n + 1])) {
+			GoTo(lineno, n);
+			PutRange(oldLine, newLine, lineno, n, n + 1);
+			n++;
+		    }
+		    GoTo(lineno, n + 1);
 		    InsStr(&newLine[n + 1], nLastChar - oLastChar);
 		}
 	    } else if (oLastChar > nLastChar) {