diff --git a/sphinx/builders/dirhtml.py b/sphinx/builders/dirhtml.py
index 40ec7b11f..25c999003 100644
--- a/sphinx/builders/dirhtml.py
+++ b/sphinx/builders/dirhtml.py
@@ -9,7 +9,7 @@
 """
 
 from os import path
-from typing import Any, Dict, Set
+from typing import Any, Dict
 
 from sphinx.application import Sphinx
 from sphinx.builders.html import StandaloneHTMLBuilder
@@ -45,10 +45,6 @@ class DirectoryHTMLBuilder(StandaloneHTMLBuilder):
 
         return outfilename
 
-    def prepare_writing(self, docnames: Set[str]) -> None:
-        super().prepare_writing(docnames)
-        self.globalcontext['no_search_suffix'] = True
-
 
 # for compatibility
 deprecated_alias('sphinx.builders.html',
diff --git a/sphinx/themes/basic/static/documentation_options.js_t b/sphinx/themes/basic/static/documentation_options.js_t
index 66d4bab88..059e8871c 100644
--- a/sphinx/themes/basic/static/documentation_options.js_t
+++ b/sphinx/themes/basic/static/documentation_options.js_t
@@ -3,7 +3,8 @@ var DOCUMENTATION_OPTIONS = {
     VERSION: '{{ release|e }}',
     LANGUAGE: '{{ language }}',
     COLLAPSE_INDEX: false,
-    FILE_SUFFIX: '{{ '' if no_search_suffix else file_suffix }}',
+    BUILDER: '{{ builder }}',
+    FILE_SUFFIX: '{{ file_suffix }}',
     HAS_SOURCE: {{ has_source|lower }},
     SOURCELINK_SUFFIX: '{{ sourcelink_suffix }}',
     NAVIGATION_WITH_KEYS: {{ 'true' if theme_navigation_with_keys|tobool else 'false'}}
diff --git a/sphinx/themes/basic/static/searchtools.js b/sphinx/themes/basic/static/searchtools.js
index 6031f9913..7e0174e1c 100644
--- a/sphinx/themes/basic/static/searchtools.js
+++ b/sphinx/themes/basic/static/searchtools.js
@@ -245,7 +245,7 @@ var Search = {
       if (results.length) {
         var item = results.pop();
         var listItem = $('<li style="display:none"></li>');
-        if (DOCUMENTATION_OPTIONS.FILE_SUFFIX === '') {
+        if (DOCUMENTATION_OPTIONS.BUILDER === 'dirhtml') {
           // dirhtml builder
           var dirname = item[0] + '/';
           if (dirname.match(/\/index\/$/)) {