diff --git a/components/svelte-portal/rollup.config.js b/components/svelte-portal/rollup.config.js
index 983f96b..c1b341b 100644
--- a/components/svelte-portal/rollup.config.js
+++ b/components/svelte-portal/rollup.config.js
@@ -59,7 +59,8 @@ export default {
 		// https://github.com/rollup/plugins/tree/master/packages/commonjs
 		resolve({
 			browser: true,
-			dedupe: ['svelte', 'stringview']
+			dedupe: ['svelte', 'stringview'],
+			extensions: ['.svelte', '.js', '.mjs']
 		}),
 		commonjs(),