diff --git a/Models/ThemeConfig/Json/LayerConfigJson.ts b/Models/ThemeConfig/Json/LayerConfigJson.ts
index 69e132e8a..4baee1063 100644
--- a/Models/ThemeConfig/Json/LayerConfigJson.ts
+++ b/Models/ThemeConfig/Json/LayerConfigJson.ts
@@ -303,8 +303,11 @@ export interface LayerConfigJson {
      */
     tagRenderings?: (
         | string
-        | { builtin: string | string[]; override: Partial<QuestionableTagRenderingConfigJson> }
-        | { id: string; builtin: string[]; override: Partial<QuestionableTagRenderingConfigJson> }
+        | {
+              id?: string
+              builtin: string | string[]
+              override: Partial<QuestionableTagRenderingConfigJson>
+          }
         | QuestionableTagRenderingConfigJson
         | (RewritableConfigJson<
               (
diff --git a/Models/ThemeConfig/TagRenderingConfig.ts b/Models/ThemeConfig/TagRenderingConfig.ts
index a20011d74..1bd4149da 100644
--- a/Models/ThemeConfig/TagRenderingConfig.ts
+++ b/Models/ThemeConfig/TagRenderingConfig.ts
@@ -335,6 +335,10 @@ export default class TagRenderingConfig {
             if (allKeys.length > 1 && !allHaveIfNot) {
                 throw `${context}: A multi-answer is defined, which generates values over multiple keys. Please define ifnot-tags too on every mapping`
             }
+
+            if (allKeys.length > 1 && this.freeform?.key !== undefined) {
+                throw `${context}: A multi-answer is defined, which generates values over multiple keys. This is incompatible with having a freeform key`
+            }
         }
     }