diff --git a/ch09_fees.adoc b/ch09_fees.adoc
index 8036acff..785afb4c 100644
--- a/ch09_fees.adoc
+++ b/ch09_fees.adoc
@@ -212,7 +212,7 @@ transaction to pay a higher total fee than the original transaction, but
 this requirement has undesired side effects and developers have been
 looking for ways to remove it at the time of writing.
 
-Bitcoin Core currently supports two variations of RBF:
+Bitcoin Core((("Bitcoin Core", "RBF variants"))) currently supports two variations of RBF:
 
 Opt-in RBF::
   An unconfirmed transaction can signal to miners and full nodes that