diff --git a/terraform/account/region/modules/lambda_function/iam.tf b/terraform/account/region/modules/lambda_function/iam.tf
index 316f27e318..12ec547bca 100644
--- a/terraform/account/region/modules/lambda_function/iam.tf
+++ b/terraform/account/region/modules/lambda_function/iam.tf
@@ -60,7 +60,7 @@ data "aws_iam_policy_document" "lambda_iam_role" {
 data "aws_iam_policy_document" "combined_iam_role_policy" {
   source_policy_documents = [
     data.aws_iam_policy_document.lambda_iam_role.json,
-    var.lambda_role_policy_document
+    var.lambda_role_policy_document != null ? var.lambda_role_policy_document : ""
   ]
 }
 resource "aws_iam_role_policy" "lambda" {