diff --git a/packages/astro/src/vite-plugin-css/index.ts b/packages/astro/src/vite-plugin-css/index.ts
index 6ee1e0bf1f4f..5c22a3c0b162 100644
--- a/packages/astro/src/vite-plugin-css/index.ts
+++ b/packages/astro/src/vite-plugin-css/index.ts
@@ -19,7 +19,9 @@ const ASTRO_CSS_EXTENSION_POST_PATTERN = '@_@';
  * Inverse function of getVirtualModulePageName().
  */
 function getComponentFromVirtualModuleCssName(virtualModulePrefix: string, id: string): string {
-	return id.slice(virtualModulePrefix.length).replace(new RegExp(ASTRO_CSS_EXTENSION_POST_PATTERN, 'g'), '.');
+	return id
+		.slice(virtualModulePrefix.length)
+		.replace(new RegExp(ASTRO_CSS_EXTENSION_POST_PATTERN, 'g'), '.');
 }
 
 /**
@@ -56,7 +58,10 @@ export function astroDevCssPlugin({ routesList, command }: AstroVitePluginOption
 				};
 			}
 			if (id.startsWith(RESOLVED_MODULE_DEV_CSS_PREFIX)) {
-				const componentPath = getComponentFromVirtualModuleCssName(RESOLVED_MODULE_DEV_CSS_PREFIX, id);
+				const componentPath = getComponentFromVirtualModuleCssName(
+					RESOLVED_MODULE_DEV_CSS_PREFIX,
+					id,
+				);
 				const cssSet = routeCssMap.get(componentPath) || new Set<ImportedDevStyle>();
 				return {
 					code: `export const css = new Set(${JSON.stringify(Array.from(cssSet.values()))})`,
diff --git a/packages/astro/src/vite-plugin-pages/util.ts b/packages/astro/src/vite-plugin-pages/util.ts
index 4ca1dc3815a7..8767cfb7d9c4 100644
--- a/packages/astro/src/vite-plugin-pages/util.ts
+++ b/packages/astro/src/vite-plugin-pages/util.ts
@@ -1,4 +1,4 @@
-import { extname } from 'node:path';
+import { fileExtension } from '@astrojs/internal-helpers/path';
 
 // This is an arbitrary string that we use to replace the dot of the extension.
 const ASTRO_PAGE_EXTENSION_POST_PATTERN = '@_@';
@@ -10,7 +10,7 @@ const ASTRO_PAGE_EXTENSION_POST_PATTERN = '@_@';
  * @param path Page component path
  */
 export function getVirtualModulePageName(virtualModulePrefix: string, path: string): string {
-	const extension = extname(path);
+	const extension = fileExtension(path);
 	return (
 		virtualModulePrefix +
 		(extension.startsWith('.')