diff --git a/spec/integ/sliding-sync-sdk.spec.ts b/spec/integ/sliding-sync-sdk.spec.ts
index 643f4f7e1b..1519212060 100644
--- a/spec/integ/sliding-sync-sdk.spec.ts
+++ b/spec/integ/sliding-sync-sdk.spec.ts
@@ -44,6 +44,7 @@ import { logger } from "../../src/logger";
 import { emitPromise } from "../test-utils/test-utils";
 import { defer } from "../../src/utils";
 import { KnownMembership } from "../../src/@types/membership";
+import { SyncCryptoCallbacks } from "../../src/common-crypto/CryptoBackend";
 
 declare module "../../src/@types/event" {
     interface AccountDataEvents {
@@ -57,6 +58,7 @@ describe("SlidingSyncSdk", () => {
     let httpBackend: MockHttpBackend | undefined;
     let sdk: SlidingSyncSdk | undefined;
     let mockSlidingSync: SlidingSync | undefined;
+    let syncCryptoCallback: SyncCryptoCallbacks | undefined;
     const selfUserId = "@alice:localhost";
     const selfAccessToken = "aseukfgwef";
 
@@ -126,8 +128,9 @@ describe("SlidingSyncSdk", () => {
         mockSlidingSync = mockifySlidingSync(new SlidingSync("", new Map(), {}, client, 0));
         if (testOpts.withCrypto) {
             httpBackend!.when("GET", "/room_keys/version").respond(404, {});
-            await client!.initLegacyCrypto();
-            syncOpts.cryptoCallbacks = syncOpts.crypto = client!.crypto;
+            await client!.initRustCrypto({ useIndexedDB: false });
+            syncCryptoCallback = client!.getCrypto() as unknown as SyncCryptoCallbacks;
+            syncOpts.cryptoCallbacks = syncCryptoCallback;
         }
         httpBackend!.when("GET", "/_matrix/client/v3/pushrules").respond(200, {});
         sdk = new SlidingSyncSdk(mockSlidingSync, client, testOpts, syncOpts);
@@ -640,13 +643,6 @@ describe("SlidingSyncSdk", () => {
             ext = findExtension("e2ee");
         });
 
-        afterAll(async () => {
-            // needed else we do some async operations in the background which can cause Jest to whine:
-            // "Cannot log after tests are done. Did you forget to wait for something async in your test?"
-            // Attempted to log "Saving device tracking data null"."
-            client!.crypto!.stop();
-        });
-
         it("gets enabled on the initial request only", () => {
             expect(ext.onRequest(true)).toEqual({
                 enabled: true,
@@ -655,28 +651,28 @@ describe("SlidingSyncSdk", () => {
         });
 
         it("can update device lists", () => {
-            client!.crypto!.processDeviceLists = jest.fn();
+            syncCryptoCallback!.processDeviceLists = jest.fn();
             ext.onResponse({
                 device_lists: {
                     changed: ["@alice:localhost"],
                     left: ["@bob:localhost"],
                 },
             });
-            expect(client!.crypto!.processDeviceLists).toHaveBeenCalledWith({
+            expect(syncCryptoCallback!.processDeviceLists).toHaveBeenCalledWith({
                 changed: ["@alice:localhost"],
                 left: ["@bob:localhost"],
             });
         });
 
         it("can update OTK counts and unused fallback keys", () => {
-            client!.crypto!.processKeyCounts = jest.fn();
+            syncCryptoCallback!.processKeyCounts = jest.fn();
             ext.onResponse({
                 device_one_time_keys_count: {
                     signed_curve25519: 42,
                 },
                 device_unused_fallback_key_types: ["signed_curve25519"],
             });
-            expect(client!.crypto!.processKeyCounts).toHaveBeenCalledWith({ signed_curve25519: 42 }, [
+            expect(syncCryptoCallback!.processKeyCounts).toHaveBeenCalledWith({ signed_curve25519: 42 }, [
                 "signed_curve25519",
             ]);
         });
diff --git a/src/sliding-sync-sdk.ts b/src/sliding-sync-sdk.ts
index 8d63e749c6..abc81cad3c 100644
--- a/src/sliding-sync-sdk.ts
+++ b/src/sliding-sync-sdk.ts
@@ -30,7 +30,6 @@ import {
     SetPresence,
 } from "./sync.ts";
 import { MatrixEvent } from "./models/event.ts";
-import { Crypto } from "./crypto/index.ts";
 import { IMinimalEvent, IRoomEvent, IStateEvent, IStrippedState, ISyncResponse } from "./sync-accumulator.ts";
 import { MatrixError } from "./http-api/index.ts";
 import {
@@ -66,7 +65,7 @@ type ExtensionE2EEResponse = Pick<
 >;
 
 class ExtensionE2EE implements Extension<ExtensionE2EERequest, ExtensionE2EEResponse> {
-    public constructor(private readonly crypto: Crypto) {}
+    public constructor(private readonly crypto: SyncCryptoCallbacks) {}
 
     public name(): string {
         return "e2ee";
@@ -373,8 +372,8 @@ export class SlidingSyncSdk {
             new ExtensionTyping(this.client),
             new ExtensionReceipts(this.client),
         ];
-        if (this.syncOpts.crypto) {
-            extensions.push(new ExtensionE2EE(this.syncOpts.crypto));
+        if (this.syncOpts.cryptoCallbacks) {
+            extensions.push(new ExtensionE2EE(this.syncOpts.cryptoCallbacks));
         }
         extensions.forEach((ext) => {
             this.slidingSync.registerExtension(ext);