diff --git a/.eslintrc.js b/.eslintrc.js
index 15060abbe8..12819f6665 100644
--- a/.eslintrc.js
+++ b/.eslintrc.js
@@ -28,7 +28,7 @@ module.exports = {
     'eqeqeq': ['error', 'always', { null: 'ignore' }],
     'prefer-const': ['error', { ignoreReadBeforeAssign: true }],
     'no-var': 'error',
-    'valid-typeof': 'off',
+    'valid-typeof': 'error',
     'no-restricted-syntax': [
       'error',
       { selector: 'ForInStatement', message: 'Use Object.{keys,values,entries} instead.' },
diff --git a/packages/sdk/browser/__tests__/BrowserApi.test.ts b/packages/sdk/browser/__tests__/BrowserApi.test.ts
new file mode 100644
index 0000000000..391e1d11a0
--- /dev/null
+++ b/packages/sdk/browser/__tests__/BrowserApi.test.ts
@@ -0,0 +1,29 @@
+import { isDocument, isWindow } from '../src/BrowserApi';
+
+it('isDocument returns true when document is defined', () => {
+  expect(isDocument()).toBe(true);
+});
+
+it('isDocument returns false when document is not defined', () => {
+  const original = Object.getOwnPropertyDescriptor(globalThis, 'document');
+  Object.defineProperty(globalThis, 'document', { value: undefined, configurable: true });
+  try {
+    expect(isDocument()).toBe(false);
+  } finally {
+    Object.defineProperty(globalThis, 'document', original!);
+  }
+});
+
+it('isWindow returns true when window is defined', () => {
+  expect(isWindow()).toBe(true);
+});
+
+it('isWindow returns false when window is not defined', () => {
+  const original = Object.getOwnPropertyDescriptor(globalThis, 'window');
+  Object.defineProperty(globalThis, 'window', { value: undefined, configurable: true });
+  try {
+    expect(isWindow()).toBe(false);
+  } finally {
+    Object.defineProperty(globalThis, 'window', original!);
+  }
+});
diff --git a/packages/sdk/browser/__tests__/platform/randomUuidV4.test.ts b/packages/sdk/browser/__tests__/platform/randomUuidV4.test.ts
index 73be7647bc..748dfe547f 100644
--- a/packages/sdk/browser/__tests__/platform/randomUuidV4.test.ts
+++ b/packages/sdk/browser/__tests__/platform/randomUuidV4.test.ts
@@ -1,4 +1,4 @@
-import { fallbackUuidV4, formatDataAsUuidV4 } from '../../src/platform/randomUuidV4';
+import randomUuidV4, { fallbackUuidV4, formatDataAsUuidV4 } from '../../src/platform/randomUuidV4';
 
 it('formats conformant UUID', () => {
   // For this test we remove the random component and just inspect the variant and version.
@@ -26,3 +26,19 @@ it('formats conformant UUID', () => {
   expect(specifierB).toEqual(0x8);
   expect(specifierC).toEqual(0x8);
 });
+
+it('falls back when crypto.randomUUID is unavailable', () => {
+  const original = globalThis.crypto;
+  Object.defineProperty(globalThis, 'crypto', {
+    value: { getRandomValues: original.getRandomValues.bind(original) },
+    configurable: true,
+  });
+
+  try {
+    const uuid = randomUuidV4();
+    expect(uuid).toHaveLength(36);
+    expect(uuid[14]).toEqual('4');
+  } finally {
+    Object.defineProperty(globalThis, 'crypto', { value: original, configurable: true });
+  }
+});
diff --git a/packages/sdk/browser/src/BrowserApi.ts b/packages/sdk/browser/src/BrowserApi.ts
index a9c233b7a6..512220a3de 100644
--- a/packages/sdk/browser/src/BrowserApi.ts
+++ b/packages/sdk/browser/src/BrowserApi.ts
@@ -5,11 +5,11 @@
  */
 
 export function isDocument() {
-  return typeof document !== undefined;
+  return typeof document !== 'undefined';
 }
 
 export function isWindow() {
-  return typeof window !== undefined;
+  return typeof window !== 'undefined';
 }
 
 /**
@@ -91,7 +91,7 @@ export function getLocationHash(): string {
 }
 
 export function getCrypto(): Crypto {
-  if (typeof crypto !== undefined) {
+  if (typeof crypto !== 'undefined') {
     return crypto;
   }
   // This would indicate running in an environment that doesn't have window.crypto or self.crypto.
diff --git a/packages/sdk/browser/src/platform/randomUuidV4.ts b/packages/sdk/browser/src/platform/randomUuidV4.ts
index 0659d58f72..620cd9acc1 100644
--- a/packages/sdk/browser/src/platform/randomUuidV4.ts
+++ b/packages/sdk/browser/src/platform/randomUuidV4.ts
@@ -91,7 +91,7 @@ export function fallbackUuidV4(): string {
 }
 
 export default function randomUuidV4(): string {
-  if (typeof crypto !== undefined && typeof crypto.randomUUID === 'function') {
+  if (typeof crypto !== 'undefined' && typeof crypto.randomUUID === 'function') {
     return crypto.randomUUID();
   }
 
diff --git a/packages/telemetry/browser-telemetry/src/randomUuidV4.ts b/packages/telemetry/browser-telemetry/src/randomUuidV4.ts
index ba455a577c..7e9c065c57 100644
--- a/packages/telemetry/browser-telemetry/src/randomUuidV4.ts
+++ b/packages/telemetry/browser-telemetry/src/randomUuidV4.ts
@@ -94,7 +94,7 @@ export function fallbackUuidV4(): string {
 }
 
 export default function randomUuidV4(): string {
-  if (typeof crypto !== undefined && typeof crypto.randomUUID === 'function') {
+  if (typeof crypto !== 'undefined' && typeof crypto.randomUUID === 'function') {
     return crypto.randomUUID();
   }