_lib = None in _Initializer.__del__

gistfile1.diff

diff --git a/usb/backend/libusb1.py b/usb/backend/libusb1.py
index a90ae24..ae4ae4e 100644
--- a/usb/backend/libusb1.py
+++ b/usb/backend/libusb1.py
@@ -437,10 +437,11 @@ class _ConfigDescriptor(object):
 
 # initialize and finalize the library
 class _Initializer(object):
-    def __init__(self):
+    def __init__(self, lib):
         _check(_lib.libusb_init(None))
+        self.lib = lib
     def __del__(self):
-        _lib.libusb_exit(None)
+        self.lib.libusb_exit(None)
 
 
 # iterator for libusb devices
@@ -666,7 +667,7 @@ def get_backend():
         if _lib is None:
             _lib = _load_library()
             _setup_prototypes(_lib)
-            _init = _Initializer()
+            _init = _Initializer(_lib)
         return _LibUSB()
     except Exception:
         _logger.error('Error loading libusb 1.0 backend', exc_info=True)