diff -r 4e9d899fcb65 Lib/ast.py
--- a/Lib/ast.py	Tue Dec 13 09:06:55 2016 -0800
+++ b/Lib/ast.py	Tue Dec 13 13:41:37 2016 -0800
@@ -81,7 +81,8 @@
                     return left + right
                 else:
                     return left - right
-        raise ValueError('malformed node or string: ' + repr(node))
+        raise ValueError('malformed node or string on line {0}: {1}'.format(
+            node.lineno, repr(node)))
     return _convert(node_or_string)