Index: usr.bin/top/display.c
===================================================================
--- usr.bin/top/display.c
+++ usr.bin/top/display.c
@@ -703,16 +703,17 @@
  *	respect to screen updates).
  */

+#define NEXT_MSG_ADDLEN 5
 static char *next_msg = NULL;
 static int msglen = 0;
 /* Invariant: msglen is always the length of the message currently displayed
    on the screen (even when next_msg doesn't contain that message). */

 void
 i_message(void)
 {
-    next_msg = setup_buffer(next_msg, 5);
+    next_msg = setup_buffer(next_msg, NEXT_MSG_ADDLEN);

     while (lastline < y_message)
     {
 	fputc('\n', stdout);
@@ -960,10 +961,11 @@
     va_start(args, msgfmt);

     /* first, format the message */
-    vsnprintf(next_msg, strlen(next_msg), msgfmt, args);
+    vsnprintf(next_msg, setup_buffer_bufsiz + NEXT_MSG_ADDLEN,
+		    msgfmt, args);

     va_end(args);

     if (msglen > 0)
     {
 	/* message there already -- can we clear it? */
@@ -1350,23 +1352,23 @@

 	if (NULL == buffer) {
 		setup_buffer_bufsiz = screen_width;
-		b = calloc(setup_buffer_bufsiz + addlen, sizeof(char));
+		b = calloc(setup_buffer_bufsiz + addlen + 2, sizeof(char));
 	} else {
 		if (screen_width > setup_buffer_bufsiz) {
 			setup_buffer_bufsiz = screen_width;
 			free(buffer);
-			b = calloc(setup_buffer_bufsiz + addlen,
+			b = calloc(setup_buffer_bufsiz + addlen + 2,
 					sizeof(char));
 		} else {
 			b = buffer;
 		}
 	}

 	if (NULL == b) {
 		fprintf(stderr, "%s: can't allocate sufficient memory\n",
 				myname);
 		exit(4);
 	}

 	return b;
 }