diff --git a/src/api/export.ts b/src/api/export.ts
index e2f7f5d..482ba51 100644
--- a/src/api/export.ts
+++ b/src/api/export.ts
@@ -38,6 +38,8 @@ async function _export({
 	oninfo = noop,
 	onfile = noop
 }: Opts = {}) {
+	basepath = basepath.replace(/^\//, '')
+
 	cwd = path.resolve(cwd);
 	static_files = path.resolve(cwd, static_files);
 	build_dir = path.resolve(cwd, build_dir);
diff --git a/test/apps/with-basepath/test.ts b/test/apps/with-basepath/test.ts
index f535b03..93bbcbf 100644
--- a/test/apps/with-basepath/test.ts
+++ b/test/apps/with-basepath/test.ts
@@ -17,7 +17,7 @@ describe('with-basepath', function() {
 
 		await api.export({
 			cwd: __dirname,
-			basepath: 'custom-basepath'
+			basepath: '/custom-basepath'
 		});
 
 		runner = new AppRunner(__dirname, '__sapper__/build/server/server.js');