diff --git a/browser-sync/browser-sync-tests.ts b/browser-sync/browser-sync-tests.ts
index 0d369e3933..2f5459c2f8 100644
--- a/browser-sync/browser-sync-tests.ts
+++ b/browser-sync/browser-sync-tests.ts
@@ -7,6 +7,13 @@ browserSync({
     }
 });
 
+// multiple base directory
+browserSync({
+    server: {
+        baseDir: ["app", "dist"]
+    }
+});
+
 browserSync({
     proxy: "yourlocal.dev"
 });
@@ -62,4 +69,4 @@ evt.on("init", function () {
     console.log("BrowserSync is running!");
 });
 
-browserSync(config);
\ No newline at end of file
+browserSync(config);
diff --git a/browser-sync/browser-sync.d.ts b/browser-sync/browser-sync.d.ts
index 5dde0e854f..4b0cd72c0e 100644
--- a/browser-sync/browser-sync.d.ts
+++ b/browser-sync/browser-sync.d.ts
@@ -65,7 +65,7 @@ declare module "browser-sync" {
         }
         
         interface ServerOptions {
-            baseDir?: string;
+            baseDir?: string | string[];
             directory?: boolean;
             index?: string;
             routes?: {[path: string]: string};
@@ -95,4 +95,4 @@ declare module "browser-sync" {
     }
 
     export = BrowserSync;
-}
\ No newline at end of file
+}