diff --git a/packages/cli/src/commands/plugin/serve/config.ts b/packages/cli/src/commands/plugin/serve/config.ts
index b3cd4559e8..7381165b5d 100644
--- a/packages/cli/src/commands/plugin/serve/config.ts
+++ b/packages/cli/src/commands/plugin/serve/config.ts
@@ -38,7 +38,7 @@ export function createConfig(paths: Paths): webpack.Configuration {
       paths.targetDevEntry,
     ],
     resolve: {
-      extensions: ['.ts', '.tsx', '.js', '.jsx'],
+      extensions: ['.ts', '.tsx', '.mjs', '.js', '.jsx'],
       modules: ['node_modules', paths.targetSrc],
       plugins: [
         new ModuleScopePlugin(