diff --git a/ebook_converter/__init__.py b/ebook_converter/__init__.py
index 767a4a2..74bd500 100644
--- a/ebook_converter/__init__.py
+++ b/ebook_converter/__init__.py
@@ -1,8 +1,6 @@
 import html
 import math
-import mimetypes
 import os
-import pkg_resources
 import re
 
 from functools import partial
@@ -11,18 +9,6 @@ from ebook_converter import constants_old
 from ebook_converter.ebooks.html_entities import html5_entities
 
 
-def init_mimetypes():
-    mimetypes.init([pkg_resources.resource_filename('ebook_converter',
-                                                    'data/mime.types')])
-
-
-def guess_extension(*args, **kwargs):
-    ext = mimetypes.guess_extension(*args, **kwargs)
-    if not ext and args and args[0] == 'application/x-palmreader':
-        ext = '.pdb'
-    return ext
-
-
 def sanitize_file_name(name, substitute='_'):
     """
     Sanitize the filename `name`. All invalid characters are replaced by
diff --git a/ebook_converter/ebooks/conversion/cli.py b/ebook_converter/ebooks/conversion/cli.py
index d4703ae..77fc0eb 100644
--- a/ebook_converter/ebooks/conversion/cli.py
+++ b/ebook_converter/ebooks/conversion/cli.py
@@ -3,16 +3,17 @@ Command line interface to conversion sub-system
 """
 import collections
 import json
+import mimetypes
 import numbers
 import optparse
 import os
+import pkg_resources
 import re
 import sys
 
 from ebook_converter.utils.config import OptionParser
 from ebook_converter.utils.logging import Log
 from ebook_converter.customize.conversion import OptionRecommendation
-from ebook_converter import init_mimetypes
 
 
 USAGE = '%prog ' + '''\
@@ -352,7 +353,8 @@ def read_sr_patterns(path, log=None):
 
 def main(args=sys.argv):
     log = Log()
-    init_mimetypes()
+    mimetypes.init([pkg_resources.resource_filename('ebook_converter',
+                                                    'data/mime.types')])
     parser, plumber = create_option_parser(args, log)
     opts, leftover_args = parser.parse_args(args)
     if len(leftover_args) > 3: