diff --git a/src/helpers/ContentType.ts b/src/helpers/ContentType.ts
index 5c0368f9..7ac64c8e 100644
--- a/src/helpers/ContentType.ts
+++ b/src/helpers/ContentType.ts
@@ -186,7 +186,7 @@ export class ContentType {
                 fields.splice(fieldIdx, 1, ...fieldGroup.fields);
               }
             } else if (field && field.type === 'fields') {
-              fields = field.fields || [];
+              field.fields = field.fields || [];
             }
           }
         }