diff --git a/spec/unit/crypto/verification/request.spec.js b/spec/unit/crypto/verification/request.spec.js
index 81d29077a..3df49c0ee 100644
--- a/spec/unit/crypto/verification/request.spec.js
+++ b/spec/unit/crypto/verification/request.spec.js
@@ -18,7 +18,7 @@ import "../../../olm-loader";
 import {verificationMethods} from "../../../../src/crypto";
 import {logger} from "../../../../src/logger";
 import {SAS} from "../../../../src/crypto/verification/SAS";
-import {makeTestClients} from './util';
+import {makeTestClients, setupWebcrypto, teardownWebcrypto} from './util';
 
 const Olm = global.Olm;
 
@@ -31,9 +31,14 @@ describe("verification request integration tests with crypto layer", function()
     }
 
     beforeAll(function() {
+        setupWebcrypto();
         return Olm.init();
     });
 
+    afterAll(() => {
+        teardownWebcrypto();
+    });
+
     it("should request and accept a verification", async function() {
         const [alice, bob] = await makeTestClients(
             [
diff --git a/spec/unit/crypto/verification/sas.spec.js b/spec/unit/crypto/verification/sas.spec.js
index 7d0ced92b..0a65083c3 100644
--- a/spec/unit/crypto/verification/sas.spec.js
+++ b/spec/unit/crypto/verification/sas.spec.js
@@ -15,7 +15,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 import "../../../olm-loader";
-import {makeTestClients} from './util';
+import {makeTestClients, setupWebcrypto, teardownWebcrypto} from './util';
 import {MatrixEvent} from "../../../../src/models/event";
 import {SAS} from "../../../../src/crypto/verification/SAS";
 import {DeviceInfo} from "../../../../src/crypto/deviceinfo";
@@ -35,9 +35,14 @@ describe("SAS verification", function() {
     }
 
     beforeAll(function() {
+        setupWebcrypto();
         return Olm.init();
     });
 
+    afterAll(() => {
+        teardownWebcrypto();
+    });
+
     it("should error on an unexpected event", async function() {
         const sas = new SAS({}, "@alice:example.com", "ABCDEFG");
         sas.handleEvent(new MatrixEvent({
diff --git a/spec/unit/crypto/verification/util.js b/spec/unit/crypto/verification/util.js
index 01749077e..b47508f9f 100644
--- a/spec/unit/crypto/verification/util.js
+++ b/spec/unit/crypto/verification/util.js
@@ -17,6 +17,7 @@ limitations under the License.
 
 import {TestClient} from '../../../TestClient';
 import {MatrixEvent} from "../../../../src/models/event";
+import nodeCrypto from "crypto";
 
 export async function makeTestClients(userInfos, options) {
     const clients = [];
@@ -102,3 +103,15 @@ export async function makeTestClients(userInfos, options) {
 
     return clients;
 }
+
+export function setupWebcrypto() {
+    global.crypto = {
+        getRandomValues: (buf) => {
+            return nodeCrypto.randomFillSync(buf);
+        },
+    };
+}
+
+export function teardownWebcrypto() {
+    global.crypto = undefined;
+}
diff --git a/spec/unit/crypto/verification/verification_request.spec.js b/spec/unit/crypto/verification/verification_request.spec.js
index 34b15d444..32f2c614d 100644
--- a/spec/unit/crypto/verification/verification_request.spec.js
+++ b/spec/unit/crypto/verification/verification_request.spec.js
@@ -19,6 +19,7 @@ import {InRoomChannel} from "../../../../src/crypto/verification/request/InRoomC
 import {ToDeviceChannel} from
     "../../../../src/crypto/verification/request/ToDeviceChannel";
 import {MatrixEvent} from "../../../../src/models/event";
+import {setupWebcrypto, teardownWebcrypto} from "./util";
 
 function makeMockClient(userId, deviceId) {
     let counter = 1;
@@ -115,6 +116,15 @@ async function distributeEvent(ownRequest, theirRequest, event) {
 }
 
 describe("verification request unit tests", function() {
+
+    beforeAll(function() {
+        setupWebcrypto();
+    });
+
+    afterAll(() => {
+        teardownWebcrypto();
+    });
+
     it("transition from UNSENT to DONE through happy path", async function() {
         const alice = makeMockClient("@alice:matrix.tld", "device1");
         const bob = makeMockClient("@bob:matrix.tld", "device1");
diff --git a/src/crypto/verification/request/VerificationRequest.js b/src/crypto/verification/request/VerificationRequest.js
index d4419e310..452bfebca 100644
--- a/src/crypto/verification/request/VerificationRequest.js
+++ b/src/crypto/verification/request/VerificationRequest.js
@@ -335,7 +335,7 @@ export class VerificationRequest extends EventEmitter {
 
     _generateSharedSecret() {
         const secretBytes = new Uint8Array(32); // 256bits
-        window.crypto.getRandomValues(secretBytes);
+        global.crypto.getRandomValues(secretBytes);
         this._sharedSecret = olmlib.encodeBase64(secretBytes);
     }