diff --git a/src/ebusd/mainloop.cpp b/src/ebusd/mainloop.cpp
index 55cf8697..e36d6c52 100755
--- a/src/ebusd/mainloop.cpp
+++ b/src/ebusd/mainloop.cpp
@@ -165,7 +165,7 @@ MainLoop::MainLoop(const struct options& opt, Device *device, MessageMap* messag
   } else {
     logError(lf_main, "error registering data handlers");
   }
-  m_newlyDefinedMessages = opt.enableDefine ? new MessageMap(true) : NULL;
+  m_newlyDefinedMessages = opt.enableDefine ? new MessageMap(true, "", false) : NULL;
 }
 
 MainLoop::~MainLoop() {
diff --git a/src/lib/ebus/message.cpp b/src/lib/ebus/message.cpp
index 3bf81e6c..1878fb43 100755
--- a/src/lib/ebus/message.cpp
+++ b/src/lib/ebus/message.cpp
@@ -474,8 +474,8 @@ result_t Message::create(const string& filename, const DataFieldTemplates* templ
   return RESULT_OK;
 }
 
-Message* Message::createScanMessage(bool broadcast) {
-  return new Message("scan", "", "", 0x07, 0x04, broadcast, DataFieldSet::getIdentFields(), !broadcast);
+Message* Message::createScanMessage(bool broadcast, bool deleteData) {
+  return new Message("scan", "", "", 0x07, 0x04, broadcast, DataFieldSet::getIdentFields(), deleteData);
 }
 
 bool Message::extractFieldNames(const string& str, bool checkAbbreviated, vector<string>* fields) {
diff --git a/src/lib/ebus/message.h b/src/lib/ebus/message.h
index 39fceb2e..b614970a 100755
--- a/src/lib/ebus/message.h
+++ b/src/lib/ebus/message.h
@@ -197,7 +197,7 @@ class Message : public AttributedItem {
    * @param broadcast true for broadcast scan message, false for scan message to be sent to a slave address.
    * @return the new scan @a Message instance.
    */
-  static Message* createScanMessage(bool broadcast = false);
+  static Message* createScanMessage(bool broadcast = false, bool deleteData = true);
 
   /**
    * Extract the known field names from the input string.
@@ -1218,12 +1218,12 @@ class MessageMap : public MappedFileReader {
    * @param addAll whether to add all messages, even if duplicate.
    * @param preferLanguage the preferred language to use, or empty.
    */
-  explicit MessageMap(bool addAll = false, const string& preferLanguage = "")
+  explicit MessageMap(bool addAll = false, const string& preferLanguage = "", bool deleteData = true)
   : MappedFileReader::MappedFileReader(true),
     m_addAll(addAll), m_additionalScanMessages(false), m_maxIdLength(0), m_maxBroadcastIdLength(0),
     m_messageCount(0), m_conditionalMessageCount(0), m_passiveMessageCount(0) {
-    m_scanMessage = Message::createScanMessage();
-    m_broadcastScanMessage = Message::createScanMessage(true);
+    m_scanMessage = Message::createScanMessage(false, deleteData);
+    m_broadcastScanMessage = Message::createScanMessage(true, false);
   }
 
   /**