diff --git a/docs/contributing.rst b/docs/contributing.rst
index 75a65fab7..98ecfaccc 100644
--- a/docs/contributing.rst
+++ b/docs/contributing.rst
@@ -169,8 +169,8 @@ challenges: HTTP, TLS-SNI, and DNS, represented by classes in `acme.challenges`.
 An authenticator plugin should implement support for at least one challenge type.
 
 An Authenticator indicates which challenges it supports by implementing
-get_chall_pref(domain) to return a sorted list of challenge types in preference
-order.
+`get_chall_pref(domain)` to return a sorted list of challenge types in
+preference order.
 
 An Authenticator must also implement `perform(achalls)`, which "performs" a list
 of challenges by, for instance, provisioning a file on an HTTP server, or