Update README.md

1 files changed, 6 insertions, 1 deletions

diff --git a/README.md b/README.md
index ba94760..7113ed7 100644
--- a/README.md
+++ b/README.md
@@ -52,7 +52,6 @@ $ python
 >>> jsonpath_expr_direct = Fields('foo').child(Slice('*')).child(Fields('baz'))  # This is equivalent
 ```
 
-
 JSONPath Syntax
 ---------------
 
@@ -151,6 +150,12 @@ The original proposal, as far as I know:
 
  * [JSONPath - XPath for JSON](http://goessner.net/articles/JSONPath/) by Stefan Goessner.
 
+Special note about PLY and docstrings
+-------------------------------------
+
+The main parsing toolkit underlying this library, [PLY](https://github.com/dabeaz/ply), does not work with
+docstrings removed. For example, `PYTHONOPTIMIZE=2` and `python -OO` will both cause a failure.
+
 
 Contributors
 ------------