diff --git a/doc/source/operations.rst b/doc/source/operations.rst
index 2085bc8..98adf57 100644
--- a/doc/source/operations.rst
+++ b/doc/source/operations.rst
@@ -114,7 +114,7 @@
 Furthermore, since the outer slashes ('/') are used to "quote" the regular
 expression, *any* slashes within the regular expression must be escaped. For
 instance, the following class mapping assigns a ``subdir-X`` class to all
-nodes that are defined in a subdirectory (using yaml_fs).
+nodes that are defined in a subdirectory (using yaml_fs)::
 
   class_mappings:
     - /^([^\/]+)\// subdir-\\1