diff --git a/src/xschem.tcl b/src/xschem.tcl
index 0c7d4093..5ccf0066 100644
--- a/src/xschem.tcl
+++ b/src/xschem.tcl
@@ -270,7 +270,7 @@ proc execute_fileevent {id} {
       if {[info exists execute(callback,$id)] && $execute(callback,$id) ne {}} {
         eval uplevel #0 [list $execute(callback,$id)]
       } 
-      unset tctx::[xschem get current_win_path]_simulate_id
+      catch {unset tctx::[xschem get current_win_path]_simulate_id}
       catch {unset execute(callback,$id)} 
       set execute(cmd,last) $execute(cmd,$id)
       set execute(data,last) $execute(data,$id)