diff --git a/resources/default_tweaks.py b/resources/default_tweaks.py
index 861e1bf70c..3e2cc4da57 100644
--- a/resources/default_tweaks.py
+++ b/resources/default_tweaks.py
@@ -366,3 +366,10 @@ server_listen_on = '0.0.0.0'
 # on at your own risk!
 unified_title_toolbar_on_osx = False
 
+#: Save original file when converting from same format to same format
+# When calibre does a conversion from the same format to the same format, for
+# example, from EPUB to EPUB, the original file is saved, so that in case the
+# conversion is poor, you can tweak the settings and run it again. By setting
+# this to False you can prevent calibre from saving the original file.
+save_original_format = True
+
diff --git a/src/calibre/ebooks/conversion/plumber.py b/src/calibre/ebooks/conversion/plumber.py
index d0d427bf74..31f125dd88 100644
--- a/src/calibre/ebooks/conversion/plumber.py
+++ b/src/calibre/ebooks/conversion/plumber.py
@@ -602,7 +602,7 @@ OptionRecommendation(name='sr3_replace',
         input_fmt = os.path.splitext(self.input)[1]
         if not input_fmt:
             raise ValueError('Input file must have an extension')
-        input_fmt = input_fmt[1:].lower()
+        input_fmt = input_fmt[1:].lower().replace('original_', '')
         self.archive_input_tdir = None
         if input_fmt in ARCHIVE_FMTS:
             self.log('Processing archive...')
diff --git a/src/calibre/ebooks/oeb/iterator.py b/src/calibre/ebooks/oeb/iterator.py
index 92a4febb6c..e584acc392 100644
--- a/src/calibre/ebooks/oeb/iterator.py
+++ b/src/calibre/ebooks/oeb/iterator.py
@@ -92,7 +92,7 @@ class EbookIterator(object):
         self.config = DynamicConfig(name='iterator')
         ext = os.path.splitext(pathtoebook)[1].replace('.', '').lower()
         ext = re.sub(r'(x{0,1})htm(l{0,1})', 'html', ext)
-        self.ebook_ext = ext
+        self.ebook_ext = ext.replace('original_', '')
 
     def search(self, text, index, backwards=False):
         text = text.lower()
diff --git a/src/calibre/gui2/actions/convert.py b/src/calibre/gui2/actions/convert.py
index 17fa0ad622..e3dc697a45 100644
--- a/src/calibre/gui2/actions/convert.py
+++ b/src/calibre/gui2/actions/convert.py
@@ -12,7 +12,7 @@ from PyQt4.Qt import QModelIndex, QMenu
 
 from calibre.gui2 import error_dialog, Dispatcher
 from calibre.gui2.tools import convert_single_ebook, convert_bulk_ebook
-from calibre.utils.config import prefs
+from calibre.utils.config import prefs, tweaks
 from calibre.gui2.actions import InterfaceAction
 from calibre.customize.ui import plugin_for_input_format
 
@@ -118,6 +118,8 @@ class ConvertAction(InterfaceAction):
     def queue_convert_jobs(self, jobs, changed, bad, rows, previous,
             converted_func, extra_job_args=[]):
         for func, args, desc, fmt, id, temp_files in jobs:
+            func, _, same_fmt = func.partition(':')
+            same_fmt = same_fmt == 'same_fmt'
             input_file = args[0]
             input_fmt = os.path.splitext(input_file)[1]
             core_usage = 1
@@ -131,6 +133,7 @@ class ConvertAction(InterfaceAction):
                 job = self.gui.job_manager.run_job(Dispatcher(converted_func),
                                             func, args=args, description=desc,
                                             core_usage=core_usage)
+                job.conversion_of_same_fmt = same_fmt
                 args = [temp_files, fmt, id]+extra_job_args
                 self.conversion_jobs[job] = tuple(args)
 
@@ -166,14 +169,18 @@ class ConvertAction(InterfaceAction):
             if job.failed:
                 self.gui.job_exception(job)
                 return
+            same_fmt = getattr(job, 'conversion_of_same_fmt', False)
             fmtf = temp_files[-1].name
             if os.stat(fmtf).st_size < 1:
                 raise Exception(_('Empty output file, '
                     'probably the conversion process crashed'))
 
+            db = self.gui.current_db
+            if same_fmt and tweaks['save_original_format']:
+                db.save_original_format(book_id, fmt, notify=False)
+
             with open(temp_files[-1].name, 'rb') as data:
-                self.gui.library_view.model().db.add_format(book_id, \
-                    fmt, data, index_is_id=True)
+                db.add_format(book_id, fmt, data, index_is_id=True)
             self.gui.status_bar.show_message(job.description + \
                     (' completed'), 2000)
         finally:
diff --git a/src/calibre/gui2/actions/view.py b/src/calibre/gui2/actions/view.py
index 6cf5c5d5af..a877a8f75f 100644
--- a/src/calibre/gui2/actions/view.py
+++ b/src/calibre/gui2/actions/view.py
@@ -128,7 +128,8 @@ class ViewAction(InterfaceAction):
             self.gui.unsetCursor()
 
     def _view_file(self, name):
-        ext = os.path.splitext(name)[1].upper().replace('.', '')
+        ext = os.path.splitext(name)[1].upper().replace('.',
+                '').replace('ORIGINAL_', '')
         viewer = 'lrfviewer' if ext == 'LRF' else 'ebook-viewer'
         internal = ext in config['internally_viewed_formats']
         self._launch_viewer(name, viewer, internal)
diff --git a/src/calibre/gui2/tools.py b/src/calibre/gui2/tools.py
index 1726c791f0..021617aa4a 100644
--- a/src/calibre/gui2/tools.py
+++ b/src/calibre/gui2/tools.py
@@ -53,7 +53,9 @@ def convert_single_ebook(parent, db, book_ids, auto_conversion=False, # {{{
                 mi = db.get_metadata(book_id, True)
                 in_file = PersistentTemporaryFile('.'+d.input_format)
                 with in_file:
-                    db.copy_format_to(book_id, d.input_format, in_file,
+                    input_fmt = db.original_fmt(book_id, d.input_format).lower()
+                    same_fmt = input_fmt == d.output_format.lower()
+                    db.copy_format_to(book_id, input_fmt, in_file,
                             index_is_id=True)
 
                 out_file = PersistentTemporaryFile('.' + d.output_format)
@@ -79,7 +81,10 @@ def convert_single_ebook(parent, db, book_ids, auto_conversion=False, # {{{
                     temp_files.append(d.cover_file)
                 args = [in_file.name, out_file.name, recs]
                 temp_files.append(out_file)
-                jobs.append(('gui_convert_override', args, desc, d.output_format.upper(), book_id, temp_files))
+                func = 'gui_convert_override'
+                if same_fmt:
+                    func += ':same_fmt'
+                jobs.append((func, args, desc, d.output_format.upper(), book_id, temp_files))
 
                 changed = True
                 d.break_cycles()
@@ -144,10 +149,12 @@ class QueueBulk(QProgressDialog):
 
         try:
             input_format = get_input_format_for_book(self.db, book_id, None)[0]
+            input_fmt = self.db.original_fmt(book_id, input_format).lower()
+            same_fmt = input_fmt == self.output_format.lower()
             mi, opf_file = create_opf_file(self.db, book_id)
             in_file = PersistentTemporaryFile('.'+input_format)
             with in_file:
-                self.db.copy_format_to(book_id, input_format, in_file,
+                self.db.copy_format_to(book_id, input_fmt, in_file,
                         index_is_id=True)
 
             out_file = PersistentTemporaryFile('.' + self.output_format)
@@ -192,7 +199,10 @@ class QueueBulk(QProgressDialog):
 
             args = [in_file.name, out_file.name, lrecs]
             temp_files.append(out_file)
-            self.jobs.append(('gui_convert_override', args, desc, self.output_format.upper(), book_id, temp_files))
+            func = 'gui_convert_override'
+            if same_fmt:
+                func += ':same_fmt'
+            self.jobs.append((func, args, desc, self.output_format.upper(), book_id, temp_files))
 
             self.changed = True
             self.setValue(self.i)
diff --git a/src/calibre/gui2/viewer/main.py b/src/calibre/gui2/viewer/main.py
index 35b25b262e..5e3d9908c1 100644
--- a/src/calibre/gui2/viewer/main.py
+++ b/src/calibre/gui2/viewer/main.py
@@ -661,12 +661,13 @@ class EbookViewer(MainWindow, Ui_EbookViewer):
     def save_current_position(self):
         if not self.get_remember_current_page_opt():
             return
-        try:
-            pos = self.view.bookmark()
-            bookmark = '%d#%s'%(self.current_index, pos)
-            self.iterator.add_bookmark(('calibre_current_page_bookmark', bookmark))
-        except:
-            traceback.print_exc()
+        if hasattr(self, 'current_index'):
+            try:
+                pos = self.view.bookmark()
+                bookmark = '%d#%s'%(self.current_index, pos)
+                self.iterator.add_bookmark(('calibre_current_page_bookmark', bookmark))
+            except:
+                traceback.print_exc()
 
     def load_ebook(self, pathtoebook):
         if self.iterator is not None:
diff --git a/src/calibre/library/database2.py b/src/calibre/library/database2.py
index ea4ca373c4..8d16ffbc52 100644
--- a/src/calibre/library/database2.py
+++ b/src/calibre/library/database2.py
@@ -1312,6 +1312,23 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
             self.notify('metadata', [id])
         return True
 
+    def save_original_format(self, book_id, fmt, notify=True):
+        fmt = fmt.upper()
+        if 'ORIGINAL' in fmt:
+            raise ValueError('Cannot save original of an original fmt')
+        opath = self.format_abspath(book_id, fmt, index_is_id=True)
+        if opath is None:
+            return False
+        nfmt = 'ORIGINAL_'+fmt
+        with lopen(opath, 'rb') as f:
+            return self.add_format(book_id, nfmt, f, index_is_id=True, notify=notify)
+
+    def original_fmt(self, book_id, fmt):
+        fmt = fmt
+        nfmt = ('ORIGINAL_%s'%fmt).upper()
+        opath = self.format_abspath(book_id, nfmt, index_is_id=True)
+        return fmt if opath is None else nfmt
+
     def delete_book(self, id, notify=True, commit=True, permanent=False):
         '''
         Removes book from the result cache and the underlying database.