diff --git a/etc/ci/manifest_changed.sh b/etc/ci/manifest_changed.sh
index f1bbf0de254f..b8c2c536f54d 100755
--- a/etc/ci/manifest_changed.sh
+++ b/etc/ci/manifest_changed.sh
@@ -1,5 +1,5 @@
 #!/bin/bash
-./mach test-wpt --manifest-update SKIP_TESTS
-diff=$(git diff --exit-code -- tests/**/MANIFEST.json)
+./mach test-wpt --manifest-update SKIP_TESTS > /dev/null
+diff=$(git diff -- tests/*/MANIFEST.json)
 echo "$diff"
 [[ ! $diff ]]