diff --git a/app-engine/demo-version-index/main.py b/app-engine/demo-version-index/main.py
index fe18d1a0f0..bc0122b872 100644
--- a/app-engine/demo-version-index/main.py
+++ b/app-engine/demo-version-index/main.py
@@ -112,7 +112,7 @@ def version_key(version):
   return version_tuple + [suffix]
 
 def get_appengine_versions():
-  if os.getenv('SERVER_SOFTWARE', '').startswith('Google App Engine/'):
+  if os.getenv('GAE_ENV', '').startswith('standard'):
     # NOTE: this doesn't return anything useful in a local dev server.
     return google.appengine.api.modules.modules.get_versions()