diff --git a/pkg/codegen/schema/pulumi.json b/pkg/codegen/schema/pulumi.json
index 4c6a6b270054..604968cebfa9 100644
--- a/pkg/codegen/schema/pulumi.json
+++ b/pkg/codegen/schema/pulumi.json
@@ -68,6 +68,7 @@
                     "format": "regex"
                 }
             },
+            "additionalProperties": false,
             "required": ["moduleFormat"]
         },
         "config": {