diff --git a/sphinx/themes/basic/static/searchtools.js_t b/sphinx/themes/basic/static/searchtools.js_t
index e863df44f..f96953b44 100644
--- a/sphinx/themes/basic/static/searchtools.js_t
+++ b/sphinx/themes/basic/static/searchtools.js_t
@@ -363,7 +363,7 @@ var Search = {
     for (i = 0; i < searchterms.length; i++) {
       var word = searchterms[i];
       // no match but word was a required one
-      if ((files = terms[word]) === null)
+      if (!(files = terms[word]))
         break;
       if (files.length === undefined) {
         files = [files];