diff --git a/typings/jquery-autocomplete/jquery.autocomplete.d.ts b/typings/jquery-autocomplete/jquery.autocomplete.d.ts
index 2a406384..01c75124 100644
--- a/typings/jquery-autocomplete/jquery.autocomplete.d.ts
+++ b/typings/jquery-autocomplete/jquery.autocomplete.d.ts
@@ -130,7 +130,7 @@ interface JQueryAutocompleteOptions {
      * Callback function or lookup array for the suggestions. It may be array of strings or suggestion object literals.
      *   -> suggestion: An object literal with the following format: { value: 'string', data: any }.
      */
-    lookup?: Function | AutocompleteSuggestion[];
+    lookup?: { (query: string, done: { (results: AutocompleteResponse): void }): void } | string[] | AutocompleteSuggestion[];
 
     /**
      * Filter function for local lookups. By default it does partial string match (case insensitive).