diff --git a/Lib/fontTools/ttLib/tables/_h_d_m_x.py b/Lib/fontTools/ttLib/tables/_h_d_m_x.py
index e5c396c4b..acfb84f84 100644
--- a/Lib/fontTools/ttLib/tables/_h_d_m_x.py
+++ b/Lib/fontTools/ttLib/tables/_h_d_m_x.py
@@ -3,6 +3,7 @@ import sstruct
 import string
 
 hdmxHeaderFormat = """
+	>   # big endian!
 	version:	H
 	numRecords:	H
 	recordSize:	l