diff --git a/Lib/os.py b/Lib/os.py
index 31002ac..2d1b29b 100644
--- a/Lib/os.py
+++ b/Lib/os.py
@@ -723,7 +723,7 @@
         """
         try:
             _urandomfd = open("/dev/urandom", O_RDONLY)
-        except:
+        except (OSError, IOError):
             raise NotImplementedError("/dev/urandom (or equivalent) not found")
         bytes = ""
         while len(bytes) < n: