diff --git a/aqhome/hexfile/flashrecord.c b/aqhome/hexfile/flashrecord.c
index 2d7469e..27afdc9 100644
--- a/aqhome/hexfile/flashrecord.c
+++ b/aqhome/hexfile/flashrecord.c
@@ -22,7 +22,7 @@
 GWEN_LIST_FUNCTIONS(AQH_FLASHRECORD, AQH_FlashRecord)
 
 
-AQH_HEXFILERECORD *_sampleAdjacentHexfileRecords(AQH_FLASHRECORD *fr, AQH_HEXFILERECORD *hrStart);
+const AQH_HEXFILERECORD *_sampleAdjacentHexfileRecords(AQH_FLASHRECORD *fr, const AQH_HEXFILERECORD *hrStart);
 
 
 
@@ -124,10 +124,10 @@ void AQH_FlashRecord_CopyAndSetData(AQH_FLASHRECORD *fr, uint32_t dataLength, co
 
 
 
-AQH_FLASHRECORD_LIST *AQH_FlashRecord_fromHexfileRecords(AQH_HEXFILERECORD_LIST *hexFileRecordList)
+AQH_FLASHRECORD_LIST *AQH_FlashRecord_fromHexfileRecords(const AQH_HEXFILERECORD_LIST *hexFileRecordList)
 {
   AQH_FLASHRECORD_LIST *flashRecordList;
-  AQH_HEXFILERECORD *hr;
+  const AQH_HEXFILERECORD *hr;
   uint32_t currentOffset=0;
 
   flashRecordList=AQH_FlashRecord_List_new();
@@ -154,7 +154,18 @@ AQH_FLASHRECORD_LIST *AQH_FlashRecord_fromHexfileRecords(AQH_HEXFILERECORD_LIST
           return NULL;
         }
         ptr=AQH_HexfileRecord_GetDataPointer(hr);
-        currentOffset=((ptr[0]<<8)+ptr[1])<<4;
+        currentOffset=((ptr[1]<<8)+ptr[0])<<4;
+      }
+      else if (t==AQH_HEXFILERECORD_TYPE_EXTLINEARADDR) {
+        const uint8_t *ptr;
+
+        if (AQH_HexfileRecord_GetByteCount(hr)<2) {
+          DBG_ERROR(AQH_LOGDOMAIN, "Invalid EXTLINEARADDR record (04) in file (too few data bytes)");
+          AQH_FlashRecord_List_free(flashRecordList);
+          return NULL;
+        }
+        ptr=AQH_HexfileRecord_GetDataPointer(hr);
+        currentOffset=((ptr[1]<<8)+ptr[0])<<16;
       }
       else if (t==AQH_HEXFILERECORD_TYPE_EOF) {
         break;
@@ -173,10 +184,10 @@ AQH_FLASHRECORD_LIST *AQH_FlashRecord_fromHexfileRecords(AQH_HEXFILERECORD_LIST
 
 
 
-AQH_HEXFILERECORD *_sampleAdjacentHexfileRecords(AQH_FLASHRECORD *fr, AQH_HEXFILERECORD *hrStart)
+const AQH_HEXFILERECORD *_sampleAdjacentHexfileRecords(AQH_FLASHRECORD *fr, const AQH_HEXFILERECORD *hrStart)
 {
-  AQH_HEXFILERECORD *hrNext;
-  AQH_HEXFILERECORD *hr;
+  const AQH_HEXFILERECORD *hrNext;
+  const AQH_HEXFILERECORD *hr;
   uint32_t len=0;
 
   hrNext=AQH_HexfileRecord_List_FindNonAdjacentDataRecord(hrStart);
diff --git a/aqhome/hexfile/flashrecord.h b/aqhome/hexfile/flashrecord.h
index 1d485a4..98579c0 100644
--- a/aqhome/hexfile/flashrecord.h
+++ b/aqhome/hexfile/flashrecord.h
@@ -21,7 +21,7 @@ GWEN_LIST_FUNCTION_LIB_DEFS(AQH_FLASHRECORD, AQH_FlashRecord, AQHOME_API)
 
 
 AQHOME_API AQH_FLASHRECORD *AQH_FlashRecord_new();
-AQHOME_API AQH_FLASHRECORD_LIST *AQH_FlashRecord_fromHexfileRecords(AQH_HEXFILERECORD_LIST *hexFileRecordList);
+AQHOME_API AQH_FLASHRECORD_LIST *AQH_FlashRecord_fromHexfileRecords(const AQH_HEXFILERECORD_LIST *hexFileRecordList);
 
 AQHOME_API void AQH_FlashRecord_free(AQH_FLASHRECORD *fr);
 
diff --git a/aqhome/hexfile/hexfile.c b/aqhome/hexfile/hexfile.c
index 20cd902..4702113 100644
--- a/aqhome/hexfile/hexfile.c
+++ b/aqhome/hexfile/hexfile.c
@@ -24,7 +24,7 @@
 static const char *_readRecord(AQH_HEXFILERECORD *hr, const char *s);
 static void _writeRecord(AQH_HEXFILERECORD *hr, GWEN_BUFFER *buffer);
 static int _sumValuesForChecksum(const AQH_HEXFILERECORD *hr);
-static int _readWord(const char *s);
+static int _readWord(const char *s); /* big endian */
 static int _readByte(const char *s);
 static int _readNibble(const char *s);
 
diff --git a/aqhome/hexfile/hexfile.h b/aqhome/hexfile/hexfile.h
index 216c79f..482814c 100644
--- a/aqhome/hexfile/hexfile.h
+++ b/aqhome/hexfile/hexfile.h
@@ -17,6 +17,10 @@
 #include <gwenhywfar/buffer.h>
 
 
+/**
+ * Reader and writer for INTEL HEX files (see https://en.wikipedia.org/wiki/Intel_HEX).
+ */
+
 
 typedef struct AQH_HEXFILE AQH_HEXFILE;
 
diff --git a/aqhome/hexfile/hexfilerecord.c b/aqhome/hexfile/hexfilerecord.c
index 25c11a1..9d8a020 100644
--- a/aqhome/hexfile/hexfilerecord.c
+++ b/aqhome/hexfile/hexfilerecord.c
@@ -143,7 +143,7 @@ void AQH_HexfileRecord_SetData(AQH_HEXFILERECORD *hr, const uint8_t *ptr, uint8_
 
 
 
-AQH_HEXFILERECORD *AQH_HexfileRecord_List_FindNonAdjacentDataRecord(AQH_HEXFILERECORD *hr)
+const AQH_HEXFILERECORD *AQH_HexfileRecord_List_FindNonAdjacentDataRecord(const AQH_HEXFILERECORD *hr)
 {
   uint16_t expectedAddr;
   int cnt=0;
diff --git a/aqhome/hexfile/hexfilerecord.h b/aqhome/hexfile/hexfilerecord.h
index ba3f8ae..6a7ec4e 100644
--- a/aqhome/hexfile/hexfilerecord.h
+++ b/aqhome/hexfile/hexfilerecord.h
@@ -55,7 +55,7 @@ AQHOME_API void AQH_HexfileRecord_SetData(AQH_HEXFILERECORD *hr, const uint8_t *
  * @return next non-contiguous or non-data record (NULL if none)
  * @param hr record to start with (i.e. whose successor are checked for continuity)
  */
-AQHOME_API AQH_HEXFILERECORD *AQH_HexfileRecord_List_FindNonAdjacentDataRecord(AQH_HEXFILERECORD *hr);
+AQHOME_API const AQH_HEXFILERECORD *AQH_HexfileRecord_List_FindNonAdjacentDataRecord(const AQH_HEXFILERECORD *hr);