diff --git a/attack-search/__tests__/search-events.test.js b/attack-search/__tests__/search-events.test.js
index f5dc8a6a20d..86af5fc0e19 100644
--- a/attack-search/__tests__/search-events.test.js
+++ b/attack-search/__tests__/search-events.test.js
@@ -83,6 +83,16 @@ describe('search event bindings', () => {
     expect(eventsForSelector('[data-search-filter-reset]')).toContain('touchend');
   });
 
+  test('search cache key includes the serialized index compatibility version', () => {
+    const { searchCacheCompatibilityVersion, searchCacheSchemaVersion } = require('../src/settings');
+
+    require('../src/index');
+
+    expect(global.localStorage.getItem).toHaveBeenCalledWith(
+      `saved_uuid_search_schema_${searchCacheSchemaVersion}-${searchCacheCompatibilityVersion}`,
+    );
+  });
+
   test('dropdown toggles open before the search service is initialized', () => {
     require('../src/index');
 
diff --git a/attack-search/__tests__/settings.test.js b/attack-search/__tests__/settings.test.js
index 9c64963c4a2..7b5fa3ff867 100644
--- a/attack-search/__tests__/settings.test.js
+++ b/attack-search/__tests__/settings.test.js
@@ -1,6 +1,16 @@
-const { searchFilePaths } = require('../src/settings');
+const {
+  searchCacheCompatibilityVersion,
+  searchFilePaths,
+} = require('../src/settings');
+const packageJson = require('../package.json');
 
 describe('search settings', () => {
+  test('includes the FlexSearch version in the cache compatibility token', () => {
+    const expectedFlexSearchVersion = packageJson.dependencies.flexsearch.replace(/^[^\d]*/, '');
+
+    expect(searchCacheCompatibilityVersion).toBe(`flexsearch-${expectedFlexSearchVersion}`);
+  });
+
   test('loads the generated sub-technique search index', () => {
     expect(searchFilePaths).toContain('sub-techniques.json');
   });
diff --git a/attack-search/src/index.js b/attack-search/src/index.js
index 68447ba36ab..d3aa49f3b30 100644
--- a/attack-search/src/index.js
+++ b/attack-search/src/index.js
@@ -10,7 +10,12 @@ const $ = require('jquery');
  */
 
 // Import required modules with the correct file extension
-const { baseURL, searchCacheSchemaVersion, searchFilePaths } = require('./settings.js');
+const {
+  baseURL,
+  searchCacheCompatibilityVersion,
+  searchCacheSchemaVersion,
+  searchFilePaths,
+} = require('./settings.js');
 const Debouncer = require('./debouncer.js');
 const SearchService = require('./search-service.js');
 const { loadSearchDocuments } = require('./search-loader.js');
@@ -26,7 +31,8 @@ const {
   closeButton,
 } = require('./components.js');
 
-const searchCacheKey = `saved_uuid_search_schema_${searchCacheSchemaVersion}`;
+const searchCacheVersion = `${searchCacheSchemaVersion}-${searchCacheCompatibilityVersion}`;
+const searchCacheKey = `saved_uuid_search_schema_${searchCacheVersion}`;
 let searchService;
 let openFilterDropdownKey = null;
 
@@ -89,7 +95,7 @@ async function initializeSearchService() {
   searchParsingIcon.show();
 
   const saved_uuid = localStorage.getItem(searchCacheKey);
-  const cachedBuildId = `${build_uuid}-search-${searchCacheSchemaVersion}`;
+  const cachedBuildId = `${build_uuid}-search-${searchCacheVersion}`;
   console.debug(`Retrieved the saved_uuid from localStorage: ${saved_uuid}`);
 
   // Check if the browser supports IndexedDB. Search service can only work in environments that support IndexedDB.
diff --git a/attack-search/src/settings.js b/attack-search/src/settings.js
index 1d5067f413e..0fa7fbaf21f 100644
--- a/attack-search/src/settings.js
+++ b/attack-search/src/settings.js
@@ -1,5 +1,9 @@
 const baseURL = ''; // TODO migrate from base_url (generated via Pelican)
+const packageJson = require('../package.json');
+
 const searchCacheSchemaVersion = 2;
+const flexSearchVersion = packageJson.dependencies.flexsearch.replace(/^[^\d]*/, '');
+const searchCacheCompatibilityVersion = `flexsearch-${flexSearchVersion}`;
 
 const searchFilePaths = [
   'campaigns.json',
@@ -19,6 +23,7 @@ const searchFilePaths = [
 ];
 module.exports = {
   baseURL,
+  searchCacheCompatibilityVersion,
   searchCacheSchemaVersion,
   searchFilePaths,
 };