diff --git a/schema.json b/schema.json
index 5656240b..bd3e763b 100644
--- a/schema.json
+++ b/schema.json
@@ -115,6 +115,7 @@
         "patternProperties": {
             "type": "object",
             "additionalProperties": { "$ref": "#" },
+            "propertyNames": { "format": "regex" },
             "default": {}
         },
         "dependencies": {