diff --git a/.changeset/curvy-humans-judge.md b/.changeset/curvy-humans-judge.md
new file mode 100644
index 0000000000..a9768726ce
--- /dev/null
+++ b/.changeset/curvy-humans-judge.md
@@ -0,0 +1,5 @@
+---
+"astro": patch
+---
+
+Fixes an issue where `astro build` writes type declaration files to `outDir` when it's outside of root directory.
diff --git a/packages/astro/src/core/build/static-build.ts b/packages/astro/src/core/build/static-build.ts
index cdd24e1c00..6e8fb0be44 100644
--- a/packages/astro/src/core/build/static-build.ts
+++ b/packages/astro/src/core/build/static-build.ts
@@ -442,6 +442,13 @@ async function cleanServerOutput(
 
 	// Clean out directly if the outDir is outside of root
 	if (out.toString() !== opts.settings.config.outDir.toString()) {
+		// Remove .d.ts files
+		const fileNames = await fs.promises.readdir(out);
+		await Promise.all(
+			fileNames
+				.filter((fileName) => fileName.endsWith('.d.ts'))
+				.map((fileName) => fs.promises.rm(new URL(fileName, out)))
+		);
 		// Copy assets before cleaning directory if outside root
 		await copyFiles(out, opts.settings.config.outDir, true);
 		await fs.promises.rm(out, { recursive: true });