diff --git a/etc/taskcluster/decision_task.py b/etc/taskcluster/decision_task.py
index 26f19c73439..0da21ffcd08 100644
--- a/etc/taskcluster/decision_task.py
+++ b/etc/taskcluster/decision_task.py
@@ -12,7 +12,7 @@ from decisionlib import CONFIG, SHARED
 def main(task_for):
     assert CONFIG.git_ref.startswith("refs/heads/")
     branch = CONFIG.git_ref[len("refs/heads/"):]
-    CONFIG.treeherder_repository_names.append("servo-" + branch)
+    CONFIG.treeherder_repository_name = "servo-" + branch
 
     if task_for == "github-push":
         # FIXME https://github.com/servo/servo/issues/22325 implement these:
@@ -39,8 +39,6 @@ def main(task_for):
                 # Add functions here as needed, in your push to that branch
             ],
             "master": [
-                # Also show these tasks in https://treeherder.mozilla.org/#/jobs?repo=servo-auto
-                lambda: CONFIG.treeherder_repository_names.append("servo-auto"),
                 upload_docs,
             ],
 
diff --git a/etc/taskcluster/decisionlib.py b/etc/taskcluster/decisionlib.py
index af9aed31ffe..e5d6cd24767 100644
--- a/etc/taskcluster/decisionlib.py
+++ b/etc/taskcluster/decisionlib.py
@@ -43,7 +43,7 @@ class Config:
         self.docker_image_buil_worker_type = None
         self.docker_images_expire_in = "1 month"
         self.repacked_msi_files_expire_in = "1 month"
-        self.treeherder_repository_names = []
+        self.treeherder_repository_name = None
 
         # Set by docker-worker:
         # https://docs.taskcluster.net/docs/reference/workers/docker-worker/docs/environment
@@ -161,9 +161,9 @@ class Task:
             "symbol": symbol,
         })
 
-        for repo in CONFIG.treeherder_repository_names:
+        if CONFIG.treeherder_repository_name:
             assert CONFIG.git_sha
-            suffix = ".v2._/%s.%s" % (repo, CONFIG.git_sha)
+            suffix = ".v2._/%s.%s" % (CONFIG.treeherder_repository_name, CONFIG.git_sha)
             self.with_routes(
                 "tc-treeherder" + suffix,
                 "tc-treeherder-staging" + suffix,