diff --git a/src/calibre/ebooks/mobi/debug/headers.py b/src/calibre/ebooks/mobi/debug/headers.py
index b38af77774..6aaafbffa3 100644
--- a/src/calibre/ebooks/mobi/debug/headers.py
+++ b/src/calibre/ebooks/mobi/debug/headers.py
@@ -377,6 +377,7 @@ class MOBIHeader(object): # {{{
 
         a('Compression: %s'%self.compression)
         a('Unused: %r'%self.unused)
+        a('Text length: %d'%self.text_length)
         a('Number of text records: %d'%self.number_of_text_records)
         a('Text record size: %d'%self.text_record_size)
         a('Encryption: %s'%self.encryption_type)
diff --git a/src/calibre/ebooks/mobi/writer2/main.py b/src/calibre/ebooks/mobi/writer2/main.py
index a1b5c06e33..e9f10a605e 100644
--- a/src/calibre/ebooks/mobi/writer2/main.py
+++ b/src/calibre/ebooks/mobi/writer2/main.py
@@ -411,6 +411,7 @@ class MobiWriter(object):
         header_fields['fdst_count'] = 1 # Why not 0? Kindlegen uses 1
         header_fields['flis_record'] = flis_number
         header_fields['fcis_record'] = fcis_number
+        header_fields['text_length'] = self.text_length
         extra_data_flags = 0b1 # Has multibyte overlap bytes
         if self.primary_index_record_idx is not None:
             extra_data_flags |= 0b10