diff --git a/includes/site.h b/includes/site.h
index 4a3556d5..0700e6bc 100644
--- a/includes/site.h
+++ b/includes/site.h
@@ -38,6 +38,10 @@
 
 /* #define DEBUG_EXPRESSION_PARSE */
 
+/* Define this if you want to watch the class matching process. */
+
+/* #define DEBUG_CLASS_MATCHING */
+
 /* Define this if you want the dhcpd.pid file to go somewhere other than
    the default (which varies from system to system, but is usually either
    /etc or /var/run. */