diff --git a/test/cases/diff-manifests.sh b/test/cases/diff-manifests.sh
index 697e13e8f..3e9ee8820 100755
--- a/test/cases/diff-manifests.sh
+++ b/test/cases/diff-manifests.sh
@@ -71,6 +71,12 @@ greenprint "Generating all manifests for merge-base (${mergebase})"
 # be broken in a PR that fixes it.
 # As long as the generation on the PR HEAD succeeds, the job should succeed.
 go run ./cmd/gen-manifests --output "${manifestdir}/${mergebase}" --workers 50
+err=$?
+merge_base_fail=""
+if (( err != 0 )); then
+    greenprint "Manifest generation on merge-base failed"
+    merge_base_fail="**NOTE:** Manifest generation on merge-base with \`main\` (${mergebase}) failed.\n\n"
+fi
 
 greenprint "Diff: ${manifestdir}/${mergebase} ${manifestdir}/PR"
 diff=$(diff -Naur "${manifestdir}"/"${mergebase}" "${manifestdir}/PR")
@@ -90,7 +96,7 @@ greenprint "Saved diff in job artifacts"
 artifacts_url="${CI_JOB_URL}/artifacts/browse/ci-artifacts"
 
 cat > "${review_data_file}" << EOF
-{"body":"⚠️ This PR introduces changes in at least one manifest (when comparing PR HEAD ${head} with the main merge-base ${mergebase}).  Please review the changes.  The changes can be found in the [artifacts of the \`Manifest-diff\` job [0]](${artifacts_url}) as \`manifests.diff\`.\n\n[0] ${artifacts_url}","event":"COMMENT"}
+{"body":"⚠️ This PR introduces changes in at least one manifest (when comparing PR HEAD ${head} with the main merge-base ${mergebase}).  Please review the changes.  The changes can be found in the [artifacts of the \`Manifest-diff\` job [0]](${artifacts_url}) as \`manifests.diff\`.\n\n${merge_base_fail}[0] ${artifacts_url}","event":"COMMENT"}
 EOF
 
 greenprint "Posting review comment"