diff --git a/nest/route.h b/nest/route.h
index 2f293c0f..e60e510e 100644
--- a/nest/route.h
+++ b/nest/route.h
@@ -301,7 +301,7 @@ typedef struct eattr {
 #define EAF_TEMP 0x80			/* A temporary attribute (the one stored in the tmp attr list) */
 
 struct adata {
-  unsigned int length;
+  unsigned int length;			/* Only size of actuall data, not including length field */
   byte data[0];
 };