diff --git a/types/typeahead/index.d.ts b/types/typeahead/index.d.ts
index 715db1d126..a000bc8f99 100644
--- a/types/typeahead/index.d.ts
+++ b/types/typeahead/index.d.ts
@@ -1186,7 +1186,7 @@ declare class Bloodhound<T> {
      * @param async Async callback.
      * @returns The data that matches query.
      */
-    public search(query: string, sync: (datums: T[]) => void, async: (datums: T[]) => void): T[];
+    public search(query: string, sync: (datums: T[]) => void, async?: (datums: T[]) => void): T[];
 
     /**
      * Returns all items from the internal search index.
diff --git a/types/typeahead/typeahead-tests.ts b/types/typeahead/typeahead-tests.ts
index fb40040dac..0123d3c70c 100644
--- a/types/typeahead/typeahead-tests.ts
+++ b/types/typeahead/typeahead-tests.ts
@@ -213,10 +213,11 @@ function test_bloodhout() {
         // search
         var sync: (datums: string[]) => {};
         var async: (datums: string[]) => {};
-        var data2: string[] = engine.search("query", sync, async);
+        var data2: string[] = engine.search("query", sync);
+        var data3: string[] = engine.search("query", sync, async);
 
         // all
-        var data3: string[] = engine.all();
+        var data4: string[] = engine.all();
 
         // clear
         var engine1: Bloodhound<string> = engine.clear();
@@ -463,4 +464,4 @@ function test_bloodhout() {
             }
         };
     }
-}
\ No newline at end of file
+}