diff --git a/build.config.ts b/build.config.ts
index d3af402e..7d24170d 100644
--- a/build.config.ts
+++ b/build.config.ts
@@ -1,6 +1,7 @@
 import type { BuildConfig } from './src/types'
 
 export default <BuildConfig> {
+  declaration: true,
   entries: [
     'src/index',
     'src/cli'
diff --git a/src/types.ts b/src/types.ts
index 0b7d2d60..0300ff14 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -30,3 +30,7 @@ export interface BuildContext extends BuildOptions {
 export interface BuildConfig extends Partial<Omit<BuildOptions, 'entries'>> {
   entries: (BuildEntry | string)[],
 }
+
+export function defineBuildConfig (config: BuildConfig): BuildConfig {
+  return config
+}