set difftofile [external_diff_get_one_file $diffidto $flist_menu_file $diffdir]
if {$difffromfile ne {} && $difftofile ne {}} {
- set cmd [concat | [shellsplit $extdifftool] \
- [list $difffromfile $difftofile]]
- if {[catch {set fl [open $cmd r]} err]} {
+ set cmd [list [shellsplit $extdifftool] $difffromfile $difftofile]
+ if {[catch {set fl [open |$cmd r]} err]} {
file delete -force $diffdir
error_popup "$extdifftool: [mc "command failed:"] $err"
} else {