diff --git a/specification/json/cper-json-section-log.json b/specification/json/cper-json-section-log.json
index d8d9239..225e3e6 100644
--- a/specification/json/cper-json-section-log.json
+++ b/specification/json/cper-json-section-log.json
@@ -13,6 +13,7 @@
             "type": "object",
             "minProperties": 1,
             "maxProperties": 1,
+            "additionalProperties": false,
             "properties": {
                 "GenericProcessor": {
                     "$ref": "./sections/cper-generic-processor.json"