diff --git a/cryptography/hazmat/backends/__init__.py b/cryptography/hazmat/backends/__init__.py
index b4ef210..e4fd94e 100644
--- a/cryptography/hazmat/backends/__init__.py
+++ b/cryptography/hazmat/backends/__init__.py
@@ -24,5 +24,6 @@
     _ALL_BACKENDS.append(commoncrypto.backend)
 
 
+_default_backend = PrioritizedMultiBackend(_ALL_BACKENDS)
 def default_backend():
-    return PrioritizedMultiBackend(_ALL_BACKENDS)
+    return _default_backend