diff --git a/src/calibre/ebooks/oeb/polish/container.py b/src/calibre/ebooks/oeb/polish/container.py
index 3bfa866237..e7dd613b32 100644
--- a/src/calibre/ebooks/oeb/polish/container.py
+++ b/src/calibre/ebooks/oeb/polish/container.py
@@ -1463,6 +1463,7 @@ def opf_to_azw3(opf, outpath, container):
     inp = plugin_for_input_format('azw3')
     outp = plugin_for_output_format('azw3')
     plumber.opts.mobi_passthrough = True
+    plumber.opts.keep_ligatures = True
     oeb = create_oebbook(container.log, opf, plumber.opts, specialize=specialize)
     set_cover(oeb)
     outp.convert(oeb, outpath, inp, plumber.opts, container.log)