diff --git a/builder.py b/builder.py
index ae39d9800..8e0ddd775 100755
--- a/builder.py
+++ b/builder.py
@@ -19,6 +19,8 @@ import ply.yacc as yacc
 
 tokens = ['LPAREN',
           'RPAREN',
+          'LBRACKET',
+          'RBRACKET',
           'VARIABLE',
           'COMMENT',
           'EQUALS',
@@ -32,6 +34,8 @@ tokens = ['LPAREN',
 t_EQUALS = '='
 t_LPAREN = '\('
 t_RPAREN = '\)'
+t_LBRACKET = '\['
+t_RBRACKET = '\]'
 t_VARIABLE = '[a-zA-Z][_0-9a-zA-Z]*'
 t_COMMENT = '\#[^\n]*'
 t_COMMA = ','
@@ -48,6 +52,7 @@ def t_error(t):
 
 def test_lexer():
     s = """hello = (something) # this = (that)
+    two = ['file1', 'file2']
     function(h)
     obj.method(lll, \\ 
     'string')