Index: openacs-4/packages/acs-templating/tcl/list-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/acs-templating/tcl/list-procs.tcl,v
diff -u -N -r1.79 -r1.80
--- openacs-4/packages/acs-templating/tcl/list-procs.tcl	30 Apr 2018 12:45:00 -0000	1.79
+++ openacs-4/packages/acs-templating/tcl/list-procs.tcl	1 May 2018 08:23:06 -0000	1.80
@@ -3206,7 +3206,7 @@
     set filter_key_filters {}
     set filter_exclude_from_key [list orderby groupby format page __list_view]
     if {[llength $filter_exclude_from_key_extra]} {
-        set filter_exclude_from_key [concat $filter_exclude_from_key $filter_exclude_from_key_extra]
+        lappend filter_exclude_from_key {*}$filter_exclude_from_key_extra
     }
     set filter_hidden_filters_url_vars {}
     # loop through all the filters in this list