diff --git a/.changeset/bright-elephants-yell.md b/.changeset/bright-elephants-yell.md
new file mode 100644
index 0000000000..9b4e71c8ae
--- /dev/null
+++ b/.changeset/bright-elephants-yell.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes a regression for `getViteConfig`, where the inline config wasn't merged in the final config.
diff --git a/packages/astro/src/config/index.ts b/packages/astro/src/config/index.ts
index aa078a9482..ee4df1c3d1 100644
--- a/packages/astro/src/config/index.ts
+++ b/packages/astro/src/config/index.ts
@@ -1,4 +1,4 @@
-import type { UserConfig } from 'vite';
+import type { UserConfig as ViteUserConfig } from 'vite';
 import type { AstroInlineConfig, AstroUserConfig } from '../@types/astro.js';
 import { Logger } from '../core/logger/core.js';
 
@@ -6,7 +6,7 @@ export function defineConfig(config: AstroUserConfig) {
 	return config;
 }
 
-export function getViteConfig(inlineConfig: UserConfig, inlineAstroConfig: AstroInlineConfig = {}) {
+export function getViteConfig(userViteConfig: ViteUserConfig, inlineAstroConfig: AstroInlineConfig = {}) {
 	// Return an async Vite config getter which exposes a resolved `mode` and `command`
 	return async ({ mode, command }: { mode: string; command: 'serve' | 'build' }) => {
 		// Vite `command` is `serve | build`, but Astro uses `dev | build`
@@ -34,8 +34,8 @@ export function getViteConfig(inlineConfig: UserConfig, inlineAstroConfig: Astro
 			dest: nodeLogDestination,
 			level: 'info',
 		});
-		const { astroConfig: config, userConfig } = await resolveConfig(inlineAstroConfig, cmd);
-		let settings = await createSettings(config, inlineConfig.root);
+		const { astroConfig: config } = await resolveConfig(inlineAstroConfig, cmd);
+		let settings = await createSettings(config, userViteConfig.root);
 		settings = await runHookConfigSetup({ settings, command: cmd, logger });
 		const viteConfig = await createVite(
 			{
@@ -48,6 +48,6 @@ export function getViteConfig(inlineConfig: UserConfig, inlineAstroConfig: Astro
 			{ settings, logger, mode }
 		);
 		await runHookConfigDone({ settings, logger });
-		return mergeConfig(viteConfig, userConfig);
+		return mergeConfig(viteConfig, userViteConfig);
 	};
 }