diff --git a/codegen/sdk-codegen/aws-models/elasticsearch-service.json b/codegen/sdk-codegen/aws-models/elasticsearch-service.json
index adffabfd40cb..e550fedd3856 100644
--- a/codegen/sdk-codegen/aws-models/elasticsearch-service.json
+++ b/codegen/sdk-codegen/aws-models/elasticsearch-service.json
@@ -5457,7 +5457,7 @@
     "com.amazonaws.elasticsearchservice#ElasticsearchVersionString": {
       "type": "string",
       "traits": {
-        "smithy.api#pattern": "^[0-9]{1}\\.[0-9]{1,2}$|^OpenSearch_[0-9]{1,2}\\.[0-9]{1,2}$"
+        "smithy.api#pattern": "^[0-9]{1}\\.[0-9]{1,2}$|^OpenSearch_[0-9]{1,2}\\.[0-9]{1,2}$|^OS_[0-9]{1,2}\\.[0-9]{1,2}$"
       }
     },
     "com.amazonaws.elasticsearchservice#EncryptionAtRestOptions": {