diff --git a/bypy/linux/__main__.py b/bypy/linux/__main__.py
index 55494f4fe8..e0b07b1055 100644
--- a/bypy/linux/__main__.py
+++ b/bypy/linux/__main__.py
@@ -15,7 +15,9 @@ from functools import partial
 from bypy.constants import (
     OUTPUT_DIR, PREFIX, SRC as CALIBRE_DIR, is64bit, python_major_minor_version
 )
-from bypy.freeze import extract_extension_modules, freeze_python, path_to_freeze_dir
+from bypy.freeze import (
+    extract_extension_modules, fix_pycryptodome, freeze_python, path_to_freeze_dir
+)
 from bypy.utils import (
     create_job, get_dll_path, mkdtemp, parallel_build, py_compile, run, walk
 )
@@ -158,6 +160,7 @@ def copy_python(env, ext_dir):
     pdir = j(env.lib_dir, 'calibre-extensions')
     if not os.path.exists(pdir):
         os.mkdir(pdir)
+    fix_pycryptodome(j(env.py_dir, 'site-packages'))
     for x in os.listdir(j(env.py_dir, 'site-packages')):
         os.rename(j(env.py_dir, 'site-packages', x), j(env.py_dir, x))
     os.rmdir(j(env.py_dir, 'site-packages'))
diff --git a/bypy/macos/__main__.py b/bypy/macos/__main__.py
index fd6c52f009..45ccae7aae 100644
--- a/bypy/macos/__main__.py
+++ b/bypy/macos/__main__.py
@@ -22,7 +22,9 @@ from itertools import repeat
 from bypy.constants import (
     OUTPUT_DIR, PREFIX, PYTHON, SRC as CALIBRE_DIR, python_major_minor_version
 )
-from bypy.freeze import extract_extension_modules, freeze_python, path_to_freeze_dir
+from bypy.freeze import (
+    extract_extension_modules, fix_pycryptodome, freeze_python, path_to_freeze_dir
+)
 from bypy.utils import current_dir, mkdtemp, py_compile, timeit, walk
 
 abspath, join, basename, dirname = os.path.abspath, os.path.join, os.path.basename, os.path.dirname
@@ -545,6 +547,7 @@ class Freeze(object):
             finally:
                 if tdir is not None:
                     shutil.rmtree(tdir)
+        fix_pycryptodome(self.site_packages)
         try:
             shutil.rmtree(join(self.site_packages, 'calibre', 'plugins'))
         except OSError as err:
diff --git a/src/calibre/test_build.py b/src/calibre/test_build.py
index 1104ddbc7c..21713cba03 100644
--- a/src/calibre/test_build.py
+++ b/src/calibre/test_build.py
@@ -30,6 +30,8 @@ class BuildTest(unittest.TestCase):
                     ctypes.WinDLL(os.path.join(base, x))
                 except Exception as err:
                     self.assertTrue(False, 'Failed to load DLL %s with error: %s' % (x, err))
+
+    def test_pycryptodome(self):
         from Crypto.Cipher import AES
         del AES