diff --git a/src/calibre/ebooks/mobi/writer2/indexer.py b/src/calibre/ebooks/mobi/writer2/indexer.py
index 873e576eb5..60b5f001cf 100644
--- a/src/calibre/ebooks/mobi/writer2/indexer.py
+++ b/src/calibre/ebooks/mobi/writer2/indexer.py
@@ -33,8 +33,10 @@ class CNCX(object): # {{{
             self.strings[item.title] = 0
             if is_periodical:
                 self.strings[item.klass] = 0
-                aut, desc = item.author, item.description
-                self.strings[item.author] = self.strings[item.description] = 0
+                if item.author:
+                    self.strings[item.author] = 0
+                if item.description:
+                    self.strings[item.description] = 0
 
         self.records = []
         offset = 0
@@ -65,8 +67,8 @@ class CNCX(object): # {{{
 class TAGX(object): # {{{
 
     BITMASKS = {11:0b1}
-    BITMASKS.update({x:i+1 for i, x in enumerate([1, 2, 3, 4, 5, 21, 22, 23])})
-    BITMASKS.update({x:i+1 for i, x in enumerate([69, 70, 71, 72, 73])})
+    BITMASKS.update({x:(1 << i) for i, x in enumerate([1, 2, 3, 4, 5, 21, 22, 23])})
+    BITMASKS.update({x:(1 << i) for i, x in enumerate([69, 70, 71, 72, 73])})
 
     NUM_VALUES = defaultdict(lambda x:1)
     NUM_VALUES[11] = 3
@@ -181,7 +183,7 @@ class IndexEntry(object):
     def entry_type(self):
         ans = 0
         for tag in self.tag_nums:
-            ans |= (1 << (TAGX.BITMASKS[tag])) # 1 << x == 2**x
+            ans |= TAGX.BITMASKS[tag]
         return ans
 
     @property
@@ -201,7 +203,7 @@ class IndexEntry(object):
             for attr in ('image_index', 'desc_offset', 'author_offset'):
                 val = getattr(self, attr)
                 if val is not None:
-                    tag = self.RTAG_MAP[attr]
+                    tag = self.TAG_VALUES[attr]
                     bm = TAGX.BITMASKS[tag]
                     flags |= bm
             buf.write(bytes(bytearray([flags])))
@@ -226,7 +228,7 @@ class IndexEntry(object):
 class PeriodicalIndexEntry(IndexEntry):
 
     def __init__(self, offset, label_offset, class_offset, depth):
-        IndexEntry.__init__(offset, label_offset)
+        IndexEntry.__init__(self, offset, label_offset)
         self.depth = depth
         self.class_offset = class_offset
         self.control_byte_count = 2
@@ -478,7 +480,7 @@ class Indexer(object): # {{{
     def create_index_record(self, secondary=False): # {{{
         header_length = 192
         buf = StringIO()
-        indices = list(SecondaryIndexEntry.entries) if secondary else self.indices
+        indices = list(SecondaryIndexEntry.entries()) if secondary else self.indices
 
         # Write index entries
         offsets = []
@@ -552,7 +554,7 @@ class Indexer(object): # {{{
         buf.write(b'\xff'*4)
 
         # Number of index entries 36-40
-        indices = list(SecondaryIndexEntry.entries) if secondary else self.indices
+        indices = list(SecondaryIndexEntry.entries()) if secondary else self.indices
         buf.write(pack(b'>I', len(indices)))
 
         # ORDT offset 40-44
diff --git a/src/calibre/ebooks/mobi/writer2/main.py b/src/calibre/ebooks/mobi/writer2/main.py
index cf35f279b7..cc03430144 100644
--- a/src/calibre/ebooks/mobi/writer2/main.py
+++ b/src/calibre/ebooks/mobi/writer2/main.py
@@ -106,7 +106,7 @@ class MobiWriter(object):
             self.log.exception('Failed to generate MOBI index:')
         else:
             self.primary_index_record_idx = len(self.records)
-            for i in xrange(len(self.records)):
+            for i in xrange(self.last_text_record_idx + 1):
                 if i == 0: continue
                 tbs = self.indexer.get_trailing_byte_sequence(i)
                 self.records[i] += encode_trailing_data(tbs)
@@ -146,6 +146,7 @@ class MobiWriter(object):
         oeb = self.oeb
         oeb.logger.info('Serializing images...')
         self.image_records = []
+        self.image_map = {}
 
         mh_href = self.masthead_offset = None
         if 'masthead' in oeb.guide:
@@ -171,10 +172,12 @@ class MobiWriter(object):
                 oeb.logger.warn('Bad image file %r' % item.href)
                 continue
             else:
+                self.image_map[item.href] = len(self.image_records)
+                self.image_records.append(data)
+
                 if item.href == mh_href:
                     self.masthead_offset = len(self.image_records) - 1
                 elif item.href == cover_href:
-                    self.image_records.append(data)
                     self.cover_offset = len(self.image_records) - 1
                     try:
                         data = rescale_image(item.data, dimen=MAX_THUMB_DIMEN,
@@ -193,7 +196,7 @@ class MobiWriter(object):
 
     def generate_text(self):
         self.oeb.logger.info('Serializing markup content...')
-        self.serializer = Serializer(self.oeb, self.images,
+        self.serializer = Serializer(self.oeb, self.image_map,
                 write_page_breaks_after_item=self.write_page_breaks_after_item)
         text = self.serializer()
         self.text_length = len(text)
@@ -539,7 +542,7 @@ class MobiWriter(object):
         else:
             # Pretend to be kindlegen 1.2
             vals = {204:201, 205:1, 206:2, 207:33307}
-        for code, val in vals:
+        for code, val in vals.iteritems():
             exth.write(pack(b'>III', code, 12, val))
             nrecs += 1