1 files changed, 2 insertions, 1 deletions

diff --git a/src/font.c b/src/font.c
index 2519599bc63..6dbda40d52f 100644
--- a/src/font.c
+++ b/src/font.c
@@ -1771,7 +1771,8 @@ font_parse_family_registry (Lisp_Object family, Lisp_Object registry, Lisp_Objec
       p1 = strchr (p0, '-');
       if (! p1)
         {
-          AUTO_STRING (extra, (&"*-*"[len && p0[len - 1] == '*']));
+          bool asterisk = len && p0[len - 1] == '*';
+          AUTO_STRING_WITH_LEN (extra, &"*-*"[asterisk], 3 - asterisk);
           registry = concat2 (registry, extra);
         }
       registry = Fdowncase (registry);