diff --git a/spec/schemas/_common.query_dsl.yaml b/spec/schemas/_common.query_dsl.yaml
index 1b5149d15..c5ec3de39 100644
--- a/spec/schemas/_common.query_dsl.yaml
+++ b/spec/schemas/_common.query_dsl.yaml
@@ -69,16 +69,13 @@ components:
           description: |-
             Returns documents that match a provided text, number, date or boolean value.
             The provided text is analyzed before matching.
-          anyOf:
-            - type: object
-              additionalProperties:
-                $ref: '#/components/schemas/MatchQuery'
-              minProperties: 1
-              maxProperties: 1
-            - type: object
-              additionalProperties: true
-              minProperties: 1
-              maxProperties: 1
+          type: object
+          additionalProperties:
+            anyOf:
+              - $ref: '#/components/schemas/MatchQuery'
+              - true
+          minProperties: 1
+          maxProperties: 1
         match_all:
           $ref: '#/components/schemas/MatchAllQuery'
         match_bool_prefix:
diff --git a/tools/src/_utils/index.ts b/tools/src/_utils/index.ts
index 2a9c67996..952dc4d7b 100644
--- a/tools/src/_utils/index.ts
+++ b/tools/src/_utils/index.ts
@@ -11,7 +11,7 @@ import { type OpenAPIV3 } from 'openapi-types'
 import { type ValidationError } from 'types'
 
 export function is_ref<O extends object> (o: MaybeRef<O>): o is OpenAPIV3.ReferenceObject {
-  return '$ref' in o
+  return typeof(o) === 'object' && '$ref' in o
 }
 
 export function is_array_schema (schema: OpenAPIV3.SchemaObject): schema is OpenAPIV3.ArraySchemaObject {