diff --git a/source/threads.tex b/source/threads.tex
index c628a8a0c7..6e4a69f31e 100644
--- a/source/threads.tex
+++ b/source/threads.tex
@@ -2600,6 +2600,7 @@
 \end{note}
 
 \pnum
+\recommended
 Implementations should ensure that no ``out-of-thin-air'' values are computed that
 circularly depend on their own computation.