diff --git a/output/schema.json b/output/schema.json
index dce6fc0b..97beaeee 100644
--- a/output/schema.json
+++ b/output/schema.json
@@ -3,7 +3,7 @@
   "$id": "https://json-schema.org/draft/2019-09/output/schema",
   "description": "A schema that validates the minimum requirements for validation output",
 
-  "oneOf": [
+  "anyOf": [
     { "$ref": "#/$defs/flag" },
     { "$ref": "#/$defs/basic" },
     { "$ref": "#/$defs/detailed" },
@@ -25,6 +25,9 @@
           "type": "string",
           "format": "uri-reference"
         },
+        "error": {
+          "type": "string"
+        },
         "errors": {
           "$ref": "#/$defs/outputUnitArray"
         },
@@ -41,7 +44,14 @@
             }
           },
           "then": {
-            "required": [ "errors" ]
+            "anyOf": [
+              {
+                "required": [ "error" ]
+              },
+              {
+                "required": [ "errors" ]
+              }
+            ]
           }
         },
         {