diff --git a/.github/workflows/playwright.yml b/.github/workflows/playwright.yml
index 3fdd09edbc6cf..beb24af744989 100644
--- a/.github/workflows/playwright.yml
+++ b/.github/workflows/playwright.yml
@@ -22,6 +22,10 @@ concurrency:
   group: playwright-${{ github.head_ref || github.run_id }}
   cancel-in-progress: true
 
+env:
+  # Branch of the vendored apps (e.g. viewer) cloned into the test server
+  BRANCH: ${{ github.base_ref || github.ref_name }}
+
 jobs:
   gate:
     runs-on: ubuntu-latest-low