diff --git a/openlp.py b/openlp.py
index 5d507606d..bbd7f1922 100755
--- a/openlp.py
+++ b/openlp.py
@@ -28,7 +28,9 @@
 ###############################################################################
 
 import sys
+import multiprocessing
 
+from openlp.core.common import is_win, is_macosx
 from openlp.core import main
 
 
@@ -36,9 +38,14 @@ if __name__ == '__main__':
     """
     Instantiate and run the application.
     """
+    # Add support for using multiprocessing from frozen Windows executable (built using PyInstaller),
+    # see https://docs.python.org/3/library/multiprocessing.html#multiprocessing.freeze_support
+    if is_win():
+        multiprocessing.freeze_support()
     # Mac OS X passes arguments like '-psn_XXXX' to the application. This argument is actually a process serial number.
     # However, this causes a conflict with other OpenLP arguments. Since we do not use this argument we can delete it
     # to avoid any potential conflicts.
-    if sys.platform.startswith('darwin'):
+    #if sys.platform.startswith('darwin'):
+    if is_macosx():
         sys.argv = [x for x in sys.argv if not x.startswith('-psn')]
     main()
diff --git a/openlp/plugins/songs/forms/duplicatesongremovalform.py b/openlp/plugins/songs/forms/duplicatesongremovalform.py
index 16867ea0b..4bcce1c44 100644
--- a/openlp/plugins/songs/forms/duplicatesongremovalform.py
+++ b/openlp/plugins/songs/forms/duplicatesongremovalform.py
@@ -33,7 +33,6 @@ The duplicate song removal logic for OpenLP.
 import logging
 import multiprocessing
 import os
-import functools
 
 from PyQt4 import QtCore, QtGui
 
@@ -47,16 +46,17 @@ from openlp.plugins.songs.lib.songcompare import songs_probably_equal
 log = logging.getLogger(__name__)
 
 
-def tuple_generator(number_of_songs):
+def song_generator(songs):
     """
-    This is a generator function to return tuples of two songs position. When completed then all songs position have
-    once been returned combined with any other songs position.
+    This is a generator function to return tuples of tuple with two songs and their position in the song array.
+    When completed then all songs have once been returned combined with any other songs.
 
-    :param number_of_songs: Number of songs in the DB.
+    :param songs: All songs in the database.
     """
-    for outer_song_counter in range(number_of_songs - 1):
-        for inner_song_counter in range(outer_song_counter + 1, number_of_songs):
-            yield (outer_song_counter, inner_song_counter)
+    for outer_song_counter in range(len(songs) - 1):
+        for inner_song_counter in range(outer_song_counter + 1, len(songs)):
+            yield ((outer_song_counter, songs[outer_song_counter].search_lyrics),
+                   (inner_song_counter, songs[inner_song_counter].search_lyrics))
 
 
 class DuplicateSongRemovalForm(OpenLPWizard, RegistryProperties):
@@ -184,9 +184,7 @@ class DuplicateSongRemovalForm(OpenLPWizard, RegistryProperties):
                 # Create a worker/process pool to check the songs.
                 process_number = max(1, multiprocessing.cpu_count() - 1)
                 pool = multiprocessing.Pool(process_number)
-                # Create array with all lyrics
-                song_lyrics = [song.search_lyrics for song in songs]
-                result = pool.imap_unordered(functools.partial(songs_probably_equal, song_lyrics), tuple_generator(len(songs)), 30)
+                result = pool.imap_unordered(songs_probably_equal, song_generator(songs), 30)
                 # Do not accept any further tasks. Also this closes the processes if all tasks are done.
                 pool.close()
                 # While the processes are still working, start to look at the results.
diff --git a/openlp/plugins/songs/lib/songcompare.py b/openlp/plugins/songs/lib/songcompare.py
index 9101245f5..ddd5e4552 100644
--- a/openlp/plugins/songs/lib/songcompare.py
+++ b/openlp/plugins/songs/lib/songcompare.py
@@ -52,14 +52,15 @@ MIN_BLOCK_SIZE = 70
 MAX_TYPO_SIZE = 3
 
 
-def songs_probably_equal(songs, pos_tupel):
+def songs_probably_equal(song_tupel):
     """
     Calculate and return whether two songs are probably equal.
 
     :param song_tupel: A tuple of two songs to compare.
     """
-    lyrics1 = songs[pos_tupel[0]]
-    lyrics2 = songs[pos_tupel[1]]
+    song1, song2 = song_tupel
+    pos1, lyrics1 = song1
+    pos2, lyrics2 = song2
     if len(lyrics1) < len(lyrics2):
         small = lyrics1
         large = lyrics2
@@ -78,7 +79,7 @@ def songs_probably_equal(songs, pos_tupel):
             length_of_equal_blocks += _op_length(element)
 
     if length_of_equal_blocks >= MIN_BLOCK_SIZE:
-        return pos_tupel[0], pos_tupel[1]
+        return pos1, pos2
     # Check 2: Similarity based on the relative length of the longest equal block.
     # Calculate the length of the largest equal block of the diff set.
     length_of_longest_equal_block = 0
@@ -86,7 +87,7 @@ def songs_probably_equal(songs, pos_tupel):
         if element[0] == "equal" and _op_length(element) > length_of_longest_equal_block:
             length_of_longest_equal_block = _op_length(element)
     if length_of_longest_equal_block > len(small) * 2 // 3:
-        return pos_tupel[0], pos_tupel[1]
+        return pos1, pos2
     # Both checks failed. We assume the songs are not equal.
     return None