--- lib/readline/display.c
+++ lib/readline/display.c	2012-07-18 08:04:36.456009352 +0000
@@ -176,7 +176,8 @@ int _rl_vis_botlin = 0;
 static int last_lmargin;
 
 /* A buffer for `modeline' messages. */
-static char msg_buf[128];
+static char *msg_buf;
+static size_t msg_buf_sz = 128;
 
 /* Non-zero forces the redisplay even if we thought it was unnecessary. */
 static int forced_display;
@@ -2139,6 +2140,32 @@ rl_message (va_alist)
 #if defined (PREFER_VARARGS)
   char *format;
 #endif
+#if defined (HAVE_VSNPRINTF)
+  int vsnprbytes;
+#endif
+
+  if (!msg_buf)
+    msg_buf = xmalloc(msg_buf_sz);
+
+#if defined (HAVE_VSNPRINTF)
+  do
+    {
+      va_end (args);
+#if defined (PREFER_STDARG)
+      va_start (args, format);
+#else
+      va_start (args);
+      format = va_arg (args, char *);
+#endif
+      vsnprbytes = vsnprintf (msg_buf, msg_buf_sz - 1, format, args);
+      if (vsnprbytes < msg_buf_sz - 1)
+	break;
+
+      msg_buf_sz += 64;
+      msg_buf = xrealloc (msg_buf, msg_buf_sz);
+    }
+  while (1);
+#else
 
 #if defined (PREFER_STDARG)
   va_start (args, format);
@@ -2147,11 +2174,8 @@ rl_message (va_alist)
   format = va_arg (args, char *);
 #endif
 
-#if defined (HAVE_VSNPRINTF)
-  vsnprintf (msg_buf, sizeof (msg_buf) - 1, format, args);
-#else
   vsprintf (msg_buf, format, args);
-  msg_buf[sizeof(msg_buf) - 1] = '\0';	/* overflow? */
+  msg_buf[msg_buf_sz - 1] = '\0';	/* overflow? */
 #endif
   va_end (args);
 
@@ -2176,8 +2200,11 @@ int
 rl_message (format, arg1, arg2)
      char *format;
 {
+  if (!msg_buf)
+    msg_buf = xmalloc(msg_buf_sz);
+
   sprintf (msg_buf, format, arg1, arg2);
-  msg_buf[sizeof(msg_buf) - 1] = '\0';	/* overflow? */
+  msg_buf[msg_buf_sz - 1] = '\0';	/* overflow? */
 
   rl_display_prompt = msg_buf;
   if (saved_local_prompt == 0)