diff --git a/src/calibre/gui2/actions/copy_to_library.py b/src/calibre/gui2/actions/copy_to_library.py
index a4e5791283..5aca55257b 100644
--- a/src/calibre/gui2/actions/copy_to_library.py
+++ b/src/calibre/gui2/actions/copy_to_library.py
@@ -98,6 +98,7 @@ class Worker(Thread):  # {{{
 
     def __init__(self, ids, db, loc, progress, done, delete_after, add_duplicates):
         Thread.__init__(self)
+        self.was_canceled = False
         self.ids = ids
         self.processed = set()
         self.db = db
@@ -105,6 +106,7 @@ class Worker(Thread):  # {{{
         self.error = None
         self.progress = progress
         self.done = done
+        self.left_after_cancel = 0
         self.delete_after = delete_after
         self.auto_merged_ids = {}
         self.add_duplicates = add_duplicates
@@ -112,6 +114,9 @@ class Worker(Thread):  # {{{
         self.check_for_duplicates = not add_duplicates and (prefs['add_formats_to_existing'] or prefs['check_for_dupes_on_ctl'])
         self.failed_books = {}
 
+    def cancel_processing(self):
+        self.was_canceled = True
+
     def run(self):
         try:
             self.doit()
@@ -144,6 +149,9 @@ class Worker(Thread):  # {{{
 
     def _doit(self, newdb):
         for i, x in enumerate(self.ids):
+            if self.was_canceled:
+                self.left_after_cancel = len(self.ids) - i
+                break
             try:
                 self.do_one(i, x, newdb)
             except Exception as err:
@@ -480,7 +488,7 @@ class CopyToLibraryAction(InterfaceAction):
         aname = _('Moving to') if delete_after else _('Copying to')
         dtitle = '%s %s'%(aname, os.path.basename(loc))
         self.pd = ProgressDialog(dtitle, min=0, max=len(ids)-1,
-                parent=self.gui, cancelable=False, icon='lt.png')
+                parent=self.gui, cancelable=True, icon='lt.png')
 
         def progress(idx, title):
             self.pd.set_msg(title)
@@ -489,8 +497,19 @@ class CopyToLibraryAction(InterfaceAction):
         self.worker = Worker(ids, db, loc, Dispatcher(progress),
                              Dispatcher(self.pd.accept), delete_after, add_duplicates)
         self.worker.start()
+        self.pd.canceled_signal.connect(self.worker.cancel_processing)
 
         self.pd.exec_()
+        self.pd.canceled_signal.disconnect()
+
+        if self.worker.left_after_cancel:
+            msg = _('The copying process was interrupted. {} books were copied.').format(len(self.worker.processed))
+            if delete_after:
+                msg += ' ' + _('No books were deleted from this library.')
+            msg += ' ' + _('The best way to resume this operation is to re-copy all the books with the option to'
+                     ' "Check for duplicates when Copying to Library" in Preferences->Adding books turned on.')
+            warning_dialog(self.gui, _('Canceled'), msg, show=True)
+            return
 
         if self.worker.error is not None:
             e, tb = self.worker.error