diff --git a/Lib/exceptions.py b/Lib/exceptions.py
index 9eba588..a81ec3c 100644
--- a/Lib/exceptions.py
+++ b/Lib/exceptions.py
@@ -105,10 +105,10 @@
 
     def __str__(self):
         if self.filename:
-            return '[Errno %d] %s: %s' % (self.errno, self.strerror,
+            return '[Errno %s] %s: %s' % (self.errno, self.strerror,
                                         self.filename)
         elif self.errno and self.strerror:
-            return '[Errno %d] %s' % (self.errno, self.strerror)
+            return '[Errno %s] %s' % (self.errno, self.strerror)
         else:
             return StandardError.__str__(self)