Index: b/subst.c
===================================================================
--- a/subst.c
+++ b/subst.c
@@ -7160,7 +7160,7 @@
       (sindex == t_index - 1 && string[sindex] == '!' && VALID_INDIR_PARAM (string[t_index])))
     {
       t_index++;
-      temp1 = string_extract (string, &t_index, "#%:-=?+/}", 0);
+      temp1 = string_extract (string, &t_index, "#%:-=?+/}", SX_VARNAME);
       name = (char *)xrealloc (name, 3 + (strlen (temp1)));
       *name = string[sindex];
       if (string[sindex] == '!')