diff --git a/configure.ac b/configure.ac
index 698e4ae9..787306dd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -21,6 +21,7 @@ NC_CXX
 NC_PLATFORM
 NC_OPTIMISATION
 NC_WARNINGS
+# NC_DEBUGGING is called further down, see notes at the call site.
 
 LT_INIT