diff --git a/python/google/protobuf/internal/api_implementation.py b/python/google/protobuf/internal/api_implementation.py
index 65caf63f8b..09af96e67c 100755
--- a/python/google/protobuf/internal/api_implementation.py
+++ b/python/google/protobuf/internal/api_implementation.py
@@ -13,6 +13,8 @@ import os
 import sys
 import warnings
 
+_GOOGLE3_PYTHON_UPB_DEFAULT = False
+
 
 def _ApiVersionToImplementationType(api_version):
   if api_version == 2: