diff --git a/README.md b/README.md
index 2d6fe7b1bfc8e989b6f3d46be4ce5ea34310ac6e..77207b6e48a8637cf10300e5002e1b55b00441f9 100644
--- a/README.md
+++ b/README.md
@@ -235,7 +235,7 @@ MSG_UPDATE      '#'
 MSG_TOPIC_MULTI '*'
 
 #Callback-Struktur
-CALLBACK_W_LENGTH _undefined_
+CALLBACK_W_LENGTH not defined
 ```
 
 # Bestellung bei Aisler