diff --git a/man2/posix_fadvise.2 b/man2/posix_fadvise.2
index e741073ef..db723c920 100644
--- a/man2/posix_fadvise.2
+++ b/man2/posix_fadvise.2
@@ -112,9 +112,13 @@ and
 .I len
 must be page-aligned.
 
-Pages that have not yet been written out will be unaffected, so if the
-application wishes to guarantee that pages will be released, it should
-call
+The implementation
+.I may
+attempt to write back dirty pages in the specified region,
+but this is not guaranteed.
+Any unwritten dirty pages will not be freed.
+If the application wishes to ensure that dirty pages will be released,
+it should call
 .BR fsync (2)
 or
 .BR fdatasync (2)