diff --git a/Doc/library/winreg.rst b/Doc/library/winreg.rst
index 473bfe3027f..4b2ed41673e 100644
--- a/Doc/library/winreg.rst
+++ b/Doc/library/winreg.rst
@@ -183,7 +183,7 @@ This module offers the following functions:
    :const:`HKEY_LOCAL_MACHINE` tree. This may or may not be true.
 
 
-.. function:: OpenKey(key, sub_key, res=0, sam=KEY_READ)
+.. function:: OpenKey(key, sub_key[, res[, sam]])
 
    Opens the specified key, returning a :dfn:`handle object`