diff --git a/Misc/NEWS b/Misc/NEWS
index a557b52..841d6d6 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -15,6 +15,9 @@
 Core and Builtins
 -----------------
 
+- Issue #4237: io.FileIO() was raising invalid warnings caused by
+  insufficient initialization of PyFileIOObject struct members.
+
 - Issue #4170: Pickling a collections.defaultdict object would crash the
   interpreter.