diff --git a/buildkite/bazelci.py b/buildkite/bazelci.py
index 6e1d33f..b793dfc 100644
--- a/buildkite/bazelci.py
+++ b/buildkite/bazelci.py
@@ -593,7 +593,7 @@
 
 
 def bazelci_builds_metadata_url(platform):
-  return "gs://bazel-builds/metadata/{0}/latest.json"
+  return "gs://bazel-builds/metadata/{0}/latest.json".format(platform)
 
 
 def latest_generation_and_build_number(platform):