diff --git a/README b/README
index 69d1689..fa3f1d7 100644
--- a/README
+++ b/README
@@ -30,7 +30,9 @@ type = bytefield
   | "float32" | "float64"
 .
 
-bytefield = "byte[" ( INTEGER | IDENT [ "*" INTEGER ]) "]".
+bytefield = "byte[" size "]".
+
+size = INTEGER | ( IDENT [ "*" INTEGER ]).
 ```
 
 The identifier of a definition line can be left empty to ignore that particular value.