diff --git a/packages/babel-helper-create-class-features-plugin/src/index.ts b/packages/babel-helper-create-class-features-plugin/src/index.ts
index 70da4597d0..25105ca085 100644
--- a/packages/babel-helper-create-class-features-plugin/src/index.ts
+++ b/packages/babel-helper-create-class-features-plugin/src/index.ts
@@ -38,6 +38,7 @@ interface Options {
   name: string;
   feature: number;
   loose?: boolean;
+  inherits?: () => Options;
   // same as PluginObject.manipulateOptions
   manipulateOptions: (options: unknown, parserOpts: ParserOptions) => void;
   // TODO(flow->ts): change to babel api
diff --git a/packages/babel-plugin-syntax-decorators/src/index.ts b/packages/babel-plugin-syntax-decorators/src/index.ts
index b0d65e4972..ccfbeedaa7 100644
--- a/packages/babel-plugin-syntax-decorators/src/index.ts
+++ b/packages/babel-plugin-syntax-decorators/src/index.ts
@@ -13,7 +13,7 @@ export default declare((api, options) => {
   ) {
     throw new Error("Unsupported decorators version: " + version);
   }
-  if (version !== undefined && options.legacy !== undefined) {
+  if (options.version !== undefined && options.legacy !== undefined) {
     throw new Error(
       'You can either specify `legacy: true` or `version: "legacy"` with decorators, not both.',
     );