diff --git a/packages/clients/src/helpers/__tests__/is-browser.browser.ts b/packages/clients/src/helpers/__tests__/is-browser.browser.ts
new file mode 100644
index 000000000..36af77921
--- /dev/null
+++ b/packages/clients/src/helpers/__tests__/is-browser.browser.ts
@@ -0,0 +1,9 @@
+/* @jest-environment jsdom */
+import { describe, expect, it } from '@jest/globals'
+import { isBrowser } from '../is-browser'
+
+describe('isBrowser', () => {
+  it('returns true by default', () => {
+    expect(isBrowser()).toBe(true)
+  })
+})
diff --git a/packages/clients/src/helpers/__tests__/is-browser.node.ts b/packages/clients/src/helpers/__tests__/is-browser.node.ts
new file mode 100644
index 000000000..1602bd363
--- /dev/null
+++ b/packages/clients/src/helpers/__tests__/is-browser.node.ts
@@ -0,0 +1,9 @@
+/* @jest-environment node */
+import { describe, expect, it } from '@jest/globals'
+import { isBrowser } from '../is-browser'
+
+describe('isBrowser', () => {
+  it('returns false by default', () => {
+    expect(isBrowser()).toBe(false)
+  })
+})
diff --git a/packages/clients/src/helpers/__tests__/is-browser.ts b/packages/clients/src/helpers/__tests__/is-browser.ts
deleted file mode 100644
index 734197d3a..000000000
--- a/packages/clients/src/helpers/__tests__/is-browser.ts
+++ /dev/null
@@ -1,16 +0,0 @@
-import { describe, expect, it } from '@jest/globals'
-import { isBrowser } from '../is-browser'
-
-describe('isBrowser', () => {
-  it('returns false by default', () => {
-    expect(isBrowser()).toBe(!!global.window)
-  })
-
-  it('returns true after defining a window', () => {
-    // @ts-expect-error Fake window/document for the test
-    global.window = { document: 'not-undefined' }
-    expect(isBrowser()).toBe(true)
-    // @ts-expect-error Reset the global variable
-    delete global.window
-  })
-})
diff --git a/packages/clients/src/scw/fetch/__tests__/build-fetcher.ts b/packages/clients/src/scw/fetch/__tests__/build-fetcher.ts
index d72ad8bf3..f7fc53ee9 100644
--- a/packages/clients/src/scw/fetch/__tests__/build-fetcher.ts
+++ b/packages/clients/src/scw/fetch/__tests__/build-fetcher.ts
@@ -43,17 +43,6 @@ describe(`buildRequest`, () => {
     })
   }
 
-  it(`has NOT the header "User-Agent" when browser is detected`, () => {
-    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-    // @ts-expect-error Fake window/document for the test
-    global.window = { document: 'not-undefined' }
-    const fReq = buildRequest(SCW_POST_REQUEST, DEFAULT_SETTINGS)
-    expect(fReq.headers.get('User-Agent')).toBeNull()
-    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
-    // @ts-expect-error Reset the global variable
-    delete global.window
-  })
-
   it(`has the custom headers`, () => {
     const mReq: ScwRequest = {
       ...SCW_POST_REQUEST,
diff --git a/packages/clients/src/scw/fetch/build-fetcher.ts b/packages/clients/src/scw/fetch/build-fetcher.ts
index 871b10252..6fe1d0d65 100644
--- a/packages/clients/src/scw/fetch/build-fetcher.ts
+++ b/packages/clients/src/scw/fetch/build-fetcher.ts
@@ -32,7 +32,9 @@ export const buildRequest = (
     body: request.body,
     headers: {
       Accept: 'application/json',
-      ...(!isBrowser() ? { 'User-Agent': settings.userAgent } : {}),
+      .../* istanbul ignore next */ (!isBrowser()
+        ? { 'User-Agent': settings.userAgent }
+        : {}),
       ...request.headers,
     },
     method: request.method,