diff --git a/main.py b/main.py
index 8b0ffec..4e27650 100755
--- a/main.py
+++ b/main.py
@@ -306,7 +306,7 @@ validoptions = frozenset(('extendedglobalexpr','breakcont','extendedtypecast',
     'lazylists','enableswitch','errmissingdefault','funcoverride','optimize',
     'optsigns','optfloats','constfold','dcr','shrinknames','addstrings',
     'foldtabs','warntabs','processpre','explicitcast',
-    'help'
+    'help','lso','expr'
     # 'clear' is handled as a special case
 ))
 
@@ -461,6 +461,14 @@ def main(argv):
             shortname = arg
     del opts
 
+    if 'lso' in options:
+        lslopt.lslcommon.LSO = True
+        options.remove('lso')
+
+    if 'expr' in options:
+        lslopt.lslcommon.IsCalc = True
+        options.remove('expr')
+
     if 'help' in options:
         Usage(argv[0], 'optimizer-options')
         return 0