diff --git a/services/filestore/config/settings.defaults.coffee b/services/filestore/config/settings.defaults.coffee
index 05a45f816d..4142be61f5 100644
--- a/services/filestore/config/settings.defaults.coffee
+++ b/services/filestore/config/settings.defaults.coffee
@@ -38,7 +38,7 @@ settings =
 				key: process.env['AWS_ACCESS_KEY_ID']
 				secret: process.env['AWS_SECRET_ACCESS_KEY']
 				endpoint: process.env['AWS_S3_ENDPOINT']
-				partSize: process.env['S3_PARTSIZE'] or (100 * 1024 * 1024)
+				partSize: process.env['AWS_S3_PARTSIZE'] or (100 * 1024 * 1024)
 
 		stores:
 			user_files: process.env['USER_FILES_BUCKET_NAME']