diff --git a/package.json b/package.json
index 9471442e8..11f33c4da 100644
--- a/package.json
+++ b/package.json
@@ -9,6 +9,7 @@
   },
   "dependencies": {
     "@juggle/resize-observer": "^3.3.1",
+    "@matrix-org/olm": "https://gitlab.matrix.org/api/v4/projects/27/packages/npm/@matrix-org/olm/-/@matrix-org/olm-3.2.8.tgz",
     "@react-aria/button": "^3.3.4",
     "@react-aria/dialog": "^3.1.4",
     "@react-aria/focus": "^3.5.0",
diff --git a/src/IndexedDBWorker.js b/src/IndexedDBWorker.js
new file mode 100644
index 000000000..0e373caf6
--- /dev/null
+++ b/src/IndexedDBWorker.js
@@ -0,0 +1,5 @@
+import { IndexedDBStoreWorker } from "matrix-js-sdk/src/indexeddb-worker";
+
+const remoteWorker = new IndexedDBStoreWorker(self.postMessage);
+
+self.onmessage = remoteWorker.onMessage;
diff --git a/src/matrix-utils.js b/src/matrix-utils.js
index 04ce3dfd8..6132b7d9a 100644
--- a/src/matrix-utils.js
+++ b/src/matrix-utils.js
@@ -3,6 +3,9 @@ import {
   GroupCallIntent,
   GroupCallType,
 } from "matrix-js-sdk/src/browser-index";
+import IndexedDBWorker from "./IndexedDBWorker?worker";
+import Olm from "@matrix-org/olm";
+import olmWasmPath from "@matrix-org/olm/olm.wasm?url";
 
 export const defaultHomeserver =
   import.meta.env.VITE_DEFAULT_HOMESERVER ||
@@ -26,11 +29,59 @@ function waitForSync(client) {
 }
 
 export async function initClient(clientOptions) {
+  // TODO: https://gitlab.matrix.org/matrix-org/olm/-/issues/10
+  window.OLM_OPTIONS = {};
+  await Olm.init({ locateFile: () => olmWasmPath });
+
+  let indexedDB;
+
+  try {
+    indexedDB = window.indexedDB;
+  } catch (e) {}
+
+  const storeOpts = {};
+
+  if (indexedDB && localStorage && !import.meta.env.DEV) {
+    storeOpts.store = new matrix.IndexedDBStore({
+      indexedDB: window.indexedDB,
+      localStorage: window.localStorage,
+      dbName: "element-call-sync",
+      workerFactory: () => new IndexedDBWorker(),
+    });
+  }
+
+  if (localStorage) {
+    storeOpts.sessionStore = new matrix.WebStorageSessionStore(localStorage);
+  }
+
+  if (indexedDB) {
+    storeOpts.cryptoStore = new matrix.IndexedDBCryptoStore(
+      indexedDB,
+      "matrix-js-sdk:crypto"
+    );
+  }
+
   const client = matrix.createClient({
+    ...storeOpts,
     ...clientOptions,
     useAuthorizationHeader: true,
   });
 
+  try {
+    await client.store.startup();
+  } catch (error) {
+    console.error(
+      "Error starting matrix client store. Falling back to memory store.",
+      error
+    );
+    client.store = new matrix.MemoryStore({ localStorage });
+    await client.store.startup();
+  }
+
+  if (client.initCrypto) {
+    await client.initCrypto();
+  }
+
   await client.startClient({
     // dirty hack to reduce chance of gappy syncs
     // should be fixed by spotting gaps and backpaginating
diff --git a/yarn.lock b/yarn.lock
index 4c921087d..985937a99 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -1320,6 +1320,10 @@
   resolved "https://registry.yarnpkg.com/@juggle/resize-observer/-/resize-observer-3.3.1.tgz#b50a781709c81e10701004214340f25475a171a0"
   integrity sha512-zMM9Ds+SawiUkakS7y94Ymqx+S0ORzpG3frZirN3l+UlXUmSUR7hF4wxCVqW+ei94JzV5kt0uXBcoOEAuiydrw==
 
+"@matrix-org/olm@https://gitlab.matrix.org/api/v4/projects/27/packages/npm/@matrix-org/olm/-/@matrix-org/olm-3.2.8.tgz":
+  version "3.2.8"
+  resolved "https://gitlab.matrix.org/api/v4/projects/27/packages/npm/@matrix-org/olm/-/@matrix-org/olm-3.2.8.tgz#8d53636d045e1776e2a2ec6613e57330dd9ce856"
+
 "@mdx-js/mdx@^1.6.22":
   version "1.6.22"
   resolved "https://registry.yarnpkg.com/@mdx-js/mdx/-/mdx-1.6.22.tgz#8a723157bf90e78f17dc0f27995398e6c731f1ba"