diff --git a/src/lib/ebus/message.cpp b/src/lib/ebus/message.cpp
index 36d009fe..7bd4eaa3 100644
--- a/src/lib/ebus/message.cpp
+++ b/src/lib/ebus/message.cpp
@@ -465,7 +465,7 @@ result_t Message::create(const string& filename, const DataFieldTemplates* templ
       return result;
     }
   }
-  if (id.size() + data->getLength(pt_masterData, maxLength) > 2 + maxLength
+  if (id.size() + data->getLength(pt_masterData, maxLength==MAX_POS ? MAX_POS-id.size() : maxLength) > 2 + maxLength
       || data->getLength(pt_slaveData, maxLength) > maxLength) {
     // max NN exceeded
     delete data;