diff --git a/modules/banner/element-web/e2e/banner.spec.ts b/modules/banner/element-web/e2e/banner.spec.ts
index fd5021e95e..edaf519492 100644
--- a/modules/banner/element-web/e2e/banner.spec.ts
+++ b/modules/banner/element-web/e2e/banner.spec.ts
@@ -166,8 +166,8 @@ test.describe("Banner", () => {
                     // Verify that the #matrixchat root got shrunk to fit rather than exploding the viewport
                     const bodyBoundingBox = await page.locator("body").boundingBox();
                     const rootBoundingBox = await page.locator("#matrixchat").boundingBox();
-                    const headerElement = await page.locator("#matrixchat").evaluate((e) => e.previousElementSibling);
-                    const headerBoundingBox = headerElement?.getBoundingClientRect();
+                    const headerBoundingBox = await page.getByTestId("banner").boundingBox();
+                    expect(rootBoundingBox!.height).toBeLessThan(bodyBoundingBox!.height);
                     expect(rootBoundingBox!.height + headerBoundingBox!.height).toEqual(bodyBoundingBox!.height);
                 });
 
diff --git a/modules/banner/element-web/src/index.tsx b/modules/banner/element-web/src/index.tsx
index f4196af06f..538fb8b3af 100644
--- a/modules/banner/element-web/src/index.tsx
+++ b/modules/banner/element-web/src/index.tsx
@@ -36,6 +36,7 @@ class BannerModule implements Module {
         }
 
         const div = document.createElement("div");
+        div.dataset.testid = "banner";
         this.api.rootNode.before(div);
 
         const root = this.api.createRoot(div);