diff --git a/mercurial/help/config.txt b/mercurial/help/config.txt
--- a/mercurial/help/config.txt
+++ b/mercurial/help/config.txt
@@ -1082,7 +1082,7 @@ The following per-host settings can be d
     This option has no effect if the per-host ``fingerprints`` option
     is set.
 
-    The format of the file is as follows:
+    The format of the file is as follows::
 
         -----BEGIN CERTIFICATE-----
         ... (certificate in base64 PEM encoding) ...