--- a/taskcluster/taskgraph/transforms/task.py
+++ b/taskcluster/taskgraph/transforms/task.py
@@ -5,16 +5,17 @@
 These transformations take a task description and turn it into a TaskCluster
 task definition (along with attributes, label, etc.).  The input to these
 transformations is generic to any kind of task, but abstracts away some of the
 complexities of worker implementations, scopes, and treeherder annotations.
 """
 
 from __future__ import absolute_import, print_function, unicode_literals
 
+import json
 import time
 
 from taskgraph.util.treeherder import split_symbol
 from taskgraph.transforms.base import (
     validate_schema,
     TransformSequence
 )
 from voluptuous import Schema, Any, Required, Optional, Extra
@@ -522,8 +523,33 @@ def build_task(config, tasks):
 
         yield {
             'label': task['label'],
             'task': task_def,
             'dependencies': task.get('dependencies', {}),
             'attributes': attributes,
             'when': task.get('when', {}),
         }
+
+
+# Check that the v2 route templates match those used by Mozharness.  This can
+# go away once Mozharness builds are no longer performed in Buildbot, and the
+# Mozharness code referencing routes.json is deleted.
+def check_v2_routes():
+    with open("testing/mozharness/configs/routes.json", "rb") as f:
+        routes_json = json.load(f)
+
+    # we only deal with the 'routes' key here
+    routes = routes_json['routes']
+
+    # we use different variables than mozharness
+    for mh, tg in [
+        ('{index}', 'index'),
+        ('{build_product}', '{product}'),
+        ('{build_name}-{build_type}', '{job-name-gecko-v2}'),
+        ('{year}.{month}.{day}.{pushdate}', '{pushdate_long}')]:
+        routes = [r.replace(mh, tg) for r in routes]
+
+    if sorted(routes) != sorted(V2_ROUTE_TEMPLATES):
+        raise Exception("V2_ROUTE_TEMPLATES does not match Mozharness's routes.json: "
+                        "%s vs %s" % (V2_ROUTE_TEMPLATES, routes))
+
+check_v2_routes()