diff --git a/mozilla/extensions/python/xpcom/nsError.py b/mozilla/extensions/python/xpcom/nsError.py
index 2284d08ba12..a513967af2c 100644
--- a/mozilla/extensions/python/xpcom/nsError.py
+++ b/mozilla/extensions/python/xpcom/nsError.py
@@ -81,6 +81,9 @@ NS_ERROR_PROXY_INVALID_OUT_PARAMETER = (  -2147418095)
 def NS_ERROR_GENERATE_FAILURE(module,code):
 	return (NS_ERROR_SEVERITY_ERROR<<31) | ((module+NS_ERROR_MODULE_BASE_OFFSET)<<16) | (code)
 
+def NS_ERROR_GENERATE_SUCCESS(module,code):
+	return (NS_ERROR_SEVERITY_SUCCESS<<31) | ((module+NS_ERROR_MODULE_BASE_OFFSET)<<16) | (code)
+
 NS_BASE_STREAM_CLOSED = NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_BASE, 2)
 NS_BASE_STREAM_OSERROR = NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_BASE, 3)
 NS_BASE_STREAM_ILLEGAL_ARGS = NS_ERROR_GENERATE_FAILURE(NS_ERROR_MODULE_BASE, 4)