diff --git a/FlatCAMApp.py b/FlatCAMApp.py
index 57d3b1a6..fe9abc0c 100644
--- a/FlatCAMApp.py
+++ b/FlatCAMApp.py
@@ -80,13 +80,13 @@ class App(QtCore.QObject):
 
     # Get Cmd Line Options
     cmd_line_shellfile = ''
-    cmd_line_shellvars = ''
+    cmd_line_shellvar = ''
 
-    cmd_line_help = "FlatCam.py --shellfile=<cmd_line_shellfile>\nFlatCam.py --shellvars=<cmd_line_shellvars"
+    cmd_line_help = "FlatCam.py --shellfile=<cmd_line_shellfile>\nFlatCam.py --shellvar=<cmd_line_shellvar>"
     try:
         # Multiprocessing pool will spawn additional processes with 'multiprocessing-fork' flag
         cmd_line_options, args = getopt.getopt(sys.argv[1:], "h:", ["shellfile=",
-                                                                    "shellvars=",
+                                                                    "shellvar=",
                                                                     "multiprocessing-fork="])
     except getopt.GetoptError:
         print(cmd_line_help)
@@ -97,8 +97,8 @@ class App(QtCore.QObject):
             sys.exit()
         elif opt == '--shellfile':
             cmd_line_shellfile = arg
-        elif opt == '--shellvars':
-            cmd_line_shellvars = arg
+        elif opt == '--shellvar':
+            cmd_line_shellvar = arg
 
     # ## Logging ###
     log = logging.getLogger('base')
@@ -2412,26 +2412,28 @@ class App(QtCore.QObject):
             except Exception as ext:
                 print("ERROR: ", ext)
                 sys.exit(2)
-        elif self.cmd_line_shellvars:
+        elif self.cmd_line_shellvar:
             try:
-                with open(self.cmd_line_shellvars, "r") as myfile:
-                    if show_splash:
-                        self.splash.showMessage('%s: %ssec\n%s' % (
-                            _("Canvas initialization started.\n"
-                              "Canvas initialization finished in"), '%.2f' % self.used_time,
-                            _("Reading Shell vars ...")),
-                                                alignment=Qt.AlignBottom | Qt.AlignLeft,
-                                                color=QtGui.QColor("gray"))
-                    cmd_line_shellvars_text = myfile.read()
-                    for line in cmd_line_shellvars_text.splitlines():
-                        var, __, var_value = line.partition('=')
-                        var = var.replace(' ', '')
-                        var_value = var_value.replace(' ', '')
-                        command_tcl = 'set {var} {var_value}'.format(var=var, var_value=var_value)
-                        self.shell._sysShell.exec_command(command_tcl, no_echo=True)
+                cnt = 0
+                command_tcl = 0
+                for i in self.cmd_line_shellvar.split(','):
+                    if i is not None:
+                        try:
+                            command_tcl = eval(i)
+                        except:
+                            command_tcl = i
+
+                    command_tcl_formatted = 'set shellvar_{nr} {cmd}'.format(cmd=str(command_tcl), nr=str(cnt))
+                    cnt += 1
+
+                    # if there are Windows paths then replace the path separator with a Unix like one
+                    if sys.platform == 'win32':
+                        command_tcl_formatted = command_tcl_formatted.replace('\\', '/')
+                    self.shell._sysShell.exec_command(command_tcl_formatted, no_echo=True)
             except Exception as ext:
                 print("ERROR: ", ext)
                 sys.exit(2)
+
         # accept some type file as command line parameter: FlatCAM project, FlatCAM preferences or scripts
         # the path/file_name must be enclosed in quotes if it contain spaces
         if App.args:
diff --git a/README.md b/README.md
index 51d8bdf5..3b14f54a 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,8 @@ CAD program, and create G-Code for Isolation routing.
 - fixed an bug where the pywrapcp name from Google OR-Tools is not defined; fix issue #316
 - if FlatCAM is started with the 'quit' or 'exit' as argument it will close immediately and it will close also another instance of FlatCAM that may be running
 - added a new command line parameter for FlatCAM named '--shellvars' which can load a text file with variables for Tcl Shell in the format: one variable assignment per line and looking like: 'a=3' without quotes
+- made --shellvars into --shellvar and make it only one list of commands passed to the Tcl. The list is separated by comma but without spaces. The variables are accessed in Tcl with the names shellvar_x where x is the index in the list of command comma separated values
+- fixed an issue in the TclShell that generated an exception IndexError which crashed the software
 
 16.09.2019
 
diff --git a/flatcamTools/ToolShell.py b/flatcamTools/ToolShell.py
index 30847cc9..42ae3983 100644
--- a/flatcamTools/ToolShell.py
+++ b/flatcamTools/ToolShell.py
@@ -142,10 +142,13 @@ class TermWidget(QWidget):
         self._append_to_browser('in', '> ' + text + '\n')
 
         if len(self._history) < 2 or self._history[-2] != text:  # don't insert duplicating items
-            if text[-1] == '\n':
-                self._history.insert(-1, text[:-1])
-            else:
-                self._history.insert(-1, text)
+            try:
+                if text[-1] == '\n':
+                    self._history.insert(-1, text[:-1])
+                else:
+                    self._history.insert(-1, text)
+            except IndexError:
+                return
 
         self._historyIndex = len(self._history) - 1