diff --git a/.changeset/chilled-coins-wash.md b/.changeset/chilled-coins-wash.md
new file mode 100644
index 000000000..df26f52d1
--- /dev/null
+++ b/.changeset/chilled-coins-wash.md
@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Fixes aliases on windows.
diff --git a/packages/astro/src/vite-plugin-config-alias/index.ts b/packages/astro/src/vite-plugin-config-alias/index.ts
index 7ed003b1b..b1e421187 100644
--- a/packages/astro/src/vite-plugin-config-alias/index.ts
+++ b/packages/astro/src/vite-plugin-config-alias/index.ts
@@ -35,7 +35,7 @@ const getConfigAlias = (cwd: string | undefined): Alias[] | null => {
   if (!compilerOptions.baseUrl) return null;
 
   // resolve the base url from the configuration file directory
-  const baseUrl = path.posix.resolve(path.posix.dirname(normalize(config.path)), normalize(compilerOptions.baseUrl));
+  const baseUrl = path.posix.resolve(path.posix.dirname(normalize(config.path).replace(/^\/?/, '/')), normalize(compilerOptions.baseUrl));
 
   /** List of compiled alias expressions. */
   const aliases: Alias[] = [];