diff --git a/resources/compiled_coffeescript.zip b/resources/compiled_coffeescript.zip
index 43781bf748..2e85fd0b33 100644
Binary files a/resources/compiled_coffeescript.zip and b/resources/compiled_coffeescript.zip differ
diff --git a/src/calibre/__init__.py b/src/calibre/__init__.py
index a0f3b49498..e64cfa30c7 100644
--- a/src/calibre/__init__.py
+++ b/src/calibre/__init__.py
@@ -40,6 +40,9 @@ def _init_mimetypes():
     global _mt_inited
     import mimetypes
     mimetypes.init([P('mime.types')])
+    mimetypes.add_type('application/epub+zip', '.epub')
+    mimetypes.add_type('application/x-mobipocket-ebook', '.mobi')
+    mimetypes.add_type('application/x-palmreader', '.pdb')
     _mt_inited = True
 
 def guess_type(*args, **kwargs):
@@ -54,6 +57,13 @@ def guess_all_extensions(*args, **kwargs):
         _init_mimetypes()
     return mimetypes.guess_all_extensions(*args, **kwargs)
 
+
+def guess_extension(*args, **kwargs):
+    import mimetypes
+    if not _mt_inited:
+        _init_mimetypes()
+    return mimetypes.guess_extension(*args, **kwargs)
+
 def get_types_map():
     import mimetypes
     if not _mt_inited:
diff --git a/src/calibre/customize/builtins.py b/src/calibre/customize/builtins.py
index 6f443a0013..da9af537f1 100644
--- a/src/calibre/customize/builtins.py
+++ b/src/calibre/customize/builtins.py
@@ -1351,6 +1351,15 @@ class StoreEbookscomStore(StoreBase):
     formats = ['EPUB', 'LIT', 'MOBI', 'PDF']
     affiliate = True
 
+class StoreEbooksGratuitsStore(StoreBase):
+    name = 'EbooksGratuits.com'
+    description = u''
+    actual_plugin = 'calibre.gui2.store.stores.ebooksgratuits_plugin:EbooksGratuitsStore'
+
+    headquarters = 'FR'
+    formats = ['EPUB', 'MOBI', 'PDF', 'PDB']
+    drm_free_only = True
+
 # class StoreEBookShoppeUKStore(StoreBase):
 #     name = 'ebookShoppe UK'
 #     author = u'Charles Haley'
@@ -1644,6 +1653,7 @@ plugins += [
     StoreEbookNLStore,
     StoreEbookpointStore,
     StoreEbookscomStore,
+    StoreEbooksGratuitsStore,
     StoreEHarlequinStore,
     StoreEKnigiStore,
     StoreEscapeMagazineStore,
diff --git a/src/calibre/gui2/store/opensearch_store.py b/src/calibre/gui2/store/opensearch_store.py
index a66418aa77..ada37de3c1 100644
--- a/src/calibre/gui2/store/opensearch_store.py
+++ b/src/calibre/gui2/store/opensearch_store.py
@@ -13,7 +13,7 @@ from lxml import etree
 
 from PyQt4.Qt import QUrl
 
-from calibre import browser
+from calibre import (browser, guess_extension)
 from calibre.gui2 import open_url
 from calibre.gui2.store import StorePlugin
 from calibre.gui2.store.search_result import SearchResult
@@ -81,7 +81,7 @@ class OpenSearchOPDSStore(StorePlugin):
                             s.detail_item = href
                         elif 'http://opds-spec.org/acquisition' in rel:
                             if type:
-                                ext = mimetypes.guess_extension(type)
+                                ext = guess_extension(type)
                                 if ext:
                                     ext = ext[1:].upper().strip()
                                     s.downloads[ext] = href