diff --git a/.github/workflows/test.yaml b/.github/workflows/test.yaml
index c39f134a..4a66f568 100644
--- a/.github/workflows/test.yaml
+++ b/.github/workflows/test.yaml
@@ -29,6 +29,8 @@ jobs:
           docker run -d -p 8888:8888 -e JUPYTER_TOKEN=secret jupyter-remote-desktop-proxy
           sleep 10
           curl 'http://localhost:8888/desktop/?token=secret' | grep 'Jupyter Remote Desktop Proxy'
+          # Test if the built JS file is present in the image
+          curl 'http://localhost:8888/desktop/dist/viewer.js?token=secret' > /dev/null
 
       # TODO: Check VNC desktop works, e.g. by comparing Playwright screenshots
       # https://playwright.dev/docs/test-snapshots