diff --git a/src/buffer.c b/src/buffer.c
index a7290ae..e91b7c8 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -3364,7 +3364,8 @@
  * or truncated if too long, fillchar is used for all whitespace.
  */
     int
-build_stl_str_hl(wp, out, outlen, fmt, use_sandbox, fillchar, maxwidth, hltab, tabtab)
+build_stl_str_hl(wp, out, outlen, fmt, use_sandbox, fillchar,
+						      maxwidth, hltab, tabtab)
     win_T	*wp;
     char_u	*out;		/* buffer to write into != NameBuff */
     size_t	outlen;		/* length of out[] */
@@ -3474,6 +3475,8 @@
 	 * Handle one '%' item.
 	 */
 	s++;
+	if (*s == NUL)  /* ignore trailing % */
+	    break;
 	if (*s == '%')
 	{
 	    if (p + 1 >= out + outlen)