diff --git a/Misc/NEWS b/Misc/NEWS
index 0dff231..1bd8a5f 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -1328,7 +1328,8 @@
 Build
 -----
 
-- Issue #1759169: Drop _XOPEN_SOURCE on Solaris.
+- Issue #1759169, #8864: Drop _XOPEN_SOURCE on Solaris, define it for
+  multiprocessing only.
 
 - Issue #8625: Turn off optimization in --with-pydebug builds with
   gcc.  (Optimization was unintentionally turned on in gcc