diff --git a/Lib/os.py b/Lib/os.py
index 20746e8..8839c10 100644
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -666,7 +666,7 @@
 
         """
         global _urandomfd
-        if not _urandomfd:
+        if _urandomfd is None:
             try:
                 _urandomfd = open("/dev/urandom", O_RDONLY)
             except: