diff --git a/src/xschem.tcl b/src/xschem.tcl
index 0e62228e..a9a05401 100644
--- a/src/xschem.tcl
+++ b/src/xschem.tcl
@@ -659,16 +659,14 @@ proc ev0 {args} {
 # does netlist post processing, called from global_(spice|vhdl|verilog)_netlist()
 proc netlist {source_file show netlist_file} {
  global XSCHEM_SHAREDIR flat_netlist netlist_dir simulate_bg
- global verilog_2001 debug_var OS verilog_bitblast
-
-
+ global verilog_2001 debug_var OS has_x verilog_bitblas
 
  # if waves are loaded turn Waves button to yellow to indicate old waves are shown
  set win_path [xschem get current_win_path]
  set top_path [xschem get top_path]
  set waves_var tctx::${win_path}_waves
  set waves_button $top_path.menubar.waves
- if {$waves_var ne $simulate_bg} {
+ if {[info exists has_x] && $waves_var ne $simulate_bg} {
    set $waves_var yellow
    $waves_button configure -bg yellow
  }
diff --git a/xschem_library/ngspice/delta_sigma.sch b/xschem_library/ngspice/delta_sigma.sch
index 58098078..8a424d3c 100644
--- a/xschem_library/ngspice/delta_sigma.sch
+++ b/xschem_library/ngspice/delta_sigma.sch
@@ -189,7 +189,7 @@ xschem raw_read $netlist_dir/[file tail [file rootname [xschem get current_name]
 C {launcher.sym} 870 -90 0 0 {name=h1 
 descr="Netlist + Simulate
 Ctrl-Left-Click" 
-tclcommand="xschem netlist; xschem simulate"
+tclcommand="xschem netlist; simulate"
 }
 C {simulator_commands.sym} 150 -380 0 0 {name=BATCH_MODE
 simulator=ngspice