diff --git a/sly/lex.py b/sly/lex.py
index a31dd80..a5dbd23 100644
--- a/sly/lex.py
+++ b/sly/lex.py
@@ -74,7 +74,11 @@ class LexerMetaDict(OrderedDict):
     '''
     def __setitem__(self, key, value):
         if key in self and not isinstance(value, property):
-            raise AttributeError('Name %s redefined' % (key))
+            if isinstance(self[key], str) and callable(value):
+                value.pattern = self[key]
+            else:
+                raise AttributeError('Name %s redefined' % (key))
+            
         super().__setitem__(key, value)
 
 class LexerMeta(type):