diff --git a/packages/vite/src/core.ts b/packages/vite/src/core.ts
index f887849bc..3529c21eb 100644
--- a/packages/vite/src/core.ts
+++ b/packages/vite/src/core.ts
@@ -37,7 +37,12 @@ export default function masterCSS(options?: PluginOptions): Plugin[] {
             enforce: 'pre',
             configResolved(config) {
                 context.config = config
-                context.entryId = fg.sync(ENTRY_MODULE_PATTERNS, { cwd: config.root, absolute: true, onlyFiles: true, caseSensitiveMatch: false })[0]
+                context.entryId = options.entryId ?? fg.sync(ENTRY_MODULE_PATTERNS, {
+                    cwd: config.root,
+                    absolute: true,
+                    onlyFiles: true,
+                    caseSensitiveMatch: false
+                )[0]
                 if (process.env.DEBUG) {
                     console.log(`[@master/css.vite] mode: ${options.mode}`)
                     console.log(`[@master/css.vite] entry: ${context.entryId || 'none'}`)
diff --git a/packages/vite/src/options.ts b/packages/vite/src/options.ts
index 665e13012..794064119 100644
--- a/packages/vite/src/options.ts
+++ b/packages/vite/src/options.ts
@@ -60,4 +60,9 @@ export interface PluginOptions {
      * Useful in Runtime
      */
     avoidFOUC?: boolean
+
+    /**
+     * Specifies which entry to use when multiple entries (i.e. main.tsx and index.ts) are present.
+     */
+    entryId?: string
 }