diff --git a/specification/json/cper-json-full-log.json b/specification/json/cper-json-full-log.json
index 91c2829..6e76255 100644
--- a/specification/json/cper-json-full-log.json
+++ b/specification/json/cper-json-full-log.json
@@ -22,9 +22,13 @@
                 "type": ["object", "null"],
                 "minProperties": 1,
                 "maxProperties": 1,
-                "required": [],
+                "required": ["message"],
                 "additionalProperties": false,
                 "properties": {
+                    "message": {
+                        "type": "string",
+                        "description": "A human readable message describing the error. This is not stable between versions."
+                    },
                     "GenericProcessor": {
                         "$ref": "./sections/cper-generic-processor.json"
                     },