diff --git a/src/calibre/ebooks/pdb/header.py b/src/calibre/ebooks/pdb/header.py
index 86ae4d3bcc..eb2a786dfd 100644
--- a/src/calibre/ebooks/pdb/header.py
+++ b/src/calibre/ebooks/pdb/header.py
@@ -67,8 +67,8 @@ class PdbHeaderReader(object):
 class PdbHeaderBuilder(object):
 
     def __init__(self, identity, title):
-        self.identity = identity.ljust(3, '\x00')[:8]
-        self.title = '%s\x00' % re.sub('[^-A-Za-z0-9 ]+', '_', title).ljust(31, '\x00')[:31].encode('ascii', 'replace')
+        self.identity = identity.ljust(3, '\x00')[:8].encode('utf-8')
+        self.title = b'%s\x00' % re.sub('[^-A-Za-z0-9 ]+', '_', title).ljust(31, '\x00')[:31].encode('ascii', 'replace')
 
     def build_header(self, section_lengths, out_stream):
         '''
@@ -85,4 +85,4 @@ class PdbHeaderBuilder(object):
         for id, record in enumerate(section_lengths):
             out_stream.write(struct.pack('>LBBBB', long_type(offset), 0, 0, 0, 0))
             offset += record
-        out_stream.write('\x00\x00')
+        out_stream.write(b'\x00\x00')
diff --git a/src/calibre/ebooks/pdb/palmdoc/writer.py b/src/calibre/ebooks/pdb/palmdoc/writer.py
index 390329b124..13d69b451f 100644
--- a/src/calibre/ebooks/pdb/palmdoc/writer.py
+++ b/src/calibre/ebooks/pdb/palmdoc/writer.py
@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+from __future__ import division
 
 '''
 Writer content to palmdoc pdb file.
@@ -57,13 +58,13 @@ class Writer(FormatWriter):
         txt_length = len(txt)
 
         txt_records = []
-        for i in range(0, (len(txt) / MAX_RECORD_SIZE) + 1):
+        for i in range(0, (len(txt) // MAX_RECORD_SIZE) + 1):
             txt_records.append(txt[i * MAX_RECORD_SIZE: (i * MAX_RECORD_SIZE) + MAX_RECORD_SIZE])
 
         return txt_records, txt_length
 
     def _header_record(self, txt_length, record_count):
-        record = ''
+        record = b''
 
         record += struct.pack('>H', 2)                  # [0:2],   PalmDoc compression. (1 = No compression).
         record += struct.pack('>H', 0)                  # [2:4],   Always 0.
@@ -73,4 +74,3 @@ class Writer(FormatWriter):
         record += struct.pack('>L', 0)                  # [12-16], Current reading position, as an offset into the uncompressed text.
 
         return record
-