allow byte literals
diff --git a/Lib/ast.py b/Lib/ast.py
index 092f077..d595c05 100644
--- a/Lib/ast.py
+++ b/Lib/ast.py
@@ -50,7 +50,7 @@
     if isinstance(node_or_string, Expression):
         node_or_string = node_or_string.body
     def _convert(node):
-        if isinstance(node, Str):
+        if isinstance(node, (Str, Bytes)):
             return node.s
         elif isinstance(node, Num):
             return node.n