diff --git a/site_ansto/instrument/mksim_config.tcl b/site_ansto/instrument/mksim_config.tcl
index 649d3369..af1f1cc1 100755
--- a/site_ansto/instrument/mksim_config.tcl
+++ b/site_ansto/instrument/mksim_config.tcl
@@ -7,7 +7,7 @@ puts "# [clock format [clock seconds] -format %c]\n"
 
 proc unknown {args} {
   set param [lindex $args 1];
-  set nonsim_motpars [list speed home hardlowerlim hardupperlim accel decel maxSpeed minSpeed maxAccel minDecel ]
+  set nonsim_motpars [list speed home hardlowerlim hardupperlim accel decel maxSpeed minSpeed maxAccel minDecel blockage_check_interval]
   if { [ lsearch -exact $nonsim_motpars $param ] == -1 } {
     puts $args;
   }