diff --git a/src/calibre/utils/fonts/sfnt/container.py b/src/calibre/utils/fonts/sfnt/container.py
index a6c0c5c81d..5ef3c157c6 100644
--- a/src/calibre/utils/fonts/sfnt/container.py
+++ b/src/calibre/utils/fonts/sfnt/container.py
@@ -55,12 +55,24 @@ class Sfnt(object):
     def __delitem__(self, key):
         del self.tables[key]
 
+    def __iter__(self):
+        '''Iterate over the table tags in optimal order as per
+        http://partners.adobe.com/public/developer/opentype/index_recs.html'''
+        keys = list(self.tables.keys())
+        order = {x:i for i, x in enumerate((b'head', b'hhea', b'maxp', b'OS/2',
+            b'hmtx', b'LTSH', b'VDMX', b'hdmx', b'cmap', b'fpgm', b'prep',
+            b'cvt ', b'loca', b'glyf', b'CFF ', b'kern', b'name', b'post',
+            b'gasp', b'PCLT', b'DSIG'))}
+        keys.sort(key=lambda x:order.get(x, 1000))
+        for x in keys:
+            yield x
+
     def pop(self, key, default=None):
         return self.tables.pop(key, default)
 
     def sizes(self):
         ans = OrderedDict()
-        for tag in sorted(self.tables):
+        for tag in self:
             ans[tag] = len(self[tag])
         return ans
 
@@ -84,7 +96,7 @@ class Sfnt(object):
         table_data = []
         offset = stream.tell() + ( calcsize(b'>4s3L') * num_tables )
         sizes = OrderedDict()
-        for tag in sorted(self.tables):
+        for tag in self:
             table = self.tables[tag]
             raw = table()
             table_len = len(raw)