diff --git a/squinnondation/messages.py b/squinnondation/messages.py
index 1cce4c6..bc427a5 100644
--- a/squinnondation/messages.py
+++ b/squinnondation/messages.py
@@ -285,6 +285,7 @@ class DataTLV(TLV):
         self.data = raw_data[14:len(self)]
         if self.data[-1] == 0:
             self.data = self.data[:-1]
+            self.length -= 1
 
     def marshal(self) -> bytes:
         return self.type.to_bytes(1, sys.byteorder) + \