diff --git a/docs/source/whatsnew/0.8.4.txt b/docs/source/whatsnew/0.8.4.txt
index fe0df981..2b86d8f1 100644
--- a/docs/source/whatsnew/0.8.4.txt
+++ b/docs/source/whatsnew/0.8.4.txt
@@ -130,6 +130,9 @@ Bug Fixes
 * Fixed issues around KeyErrors coming from history and BarData on 32-bit
   python, where Assets did not compare properly with int64s (:issue:`959`).
 
+* Fixed a bug where boolean operators were not properly implemented on
+  :class:~zipline.pipeline.Filter` (:issue:`991`).
+
 
 Performance
 ~~~~~~~~~~~