diff --git a/tcl/drivers/secop_4.tcl b/tcl/drivers/secop_4.tcl
index d3638cf..a6c5d97 100644
--- a/tcl/drivers/secop_4.tcl
+++ b/tcl/drivers/secop_4.tcl
@@ -257,7 +257,7 @@ proc secop::make_par {secopar desc {kind ""}} {
   }
   lassign [split $path /] nul obj par
   set fmtunit ""
-  if {[lsearch [list enum int double] $secoptype0] >= 0} {
+  if {[lsearch [list enum int double bool] $secoptype0] >= 0} {
     set fmtunit ""
     if {[catch {set unit [dict get $datadesc unit]}]} {
       set unit 1