diff --git a/docs/design/auth-framework.rst b/docs/design/auth-framework.rst
index 49f0def..7a742d5 100644
--- a/docs/design/auth-framework.rst
+++ b/docs/design/auth-framework.rst
@@ -408,7 +408,7 @@
 
 An IPL for each type must be registered using the following macro:
 
-::
+.. code:: c
 
     REGISTER_IMG_PARSER_LIB(_type, _name, _init, _check_int, _get_param)