diff --git a/aws-custom-cluster/template-ssl.yaml b/aws-custom-cluster/template-ssl.yaml
index 2d86a4f8..4d1a0865 100644
--- a/aws-custom-cluster/template-ssl.yaml
+++ b/aws-custom-cluster/template-ssl.yaml
@@ -146,7 +146,7 @@ Resources:
 
       Handler: index.lambda_handler
       Role: !Sub '${AcmCertificateImportLambdaExecutionRole.Arn}'
-      Runtime: python3.12
+      Runtime: python3.11
   AcmCertificateImportLambdaExecutionRole:
     Type: AWS::IAM::Role
     Properties: