--- a/taskcluster/taskgraph/transforms/job/toolchain.py
+++ b/taskcluster/taskgraph/transforms/job/toolchain.py
@@ -111,16 +111,19 @@ def docker_worker_toolchain(config, job,
             'docker-worker:relengapi-proxy:tooltool.download.public',
         ])
         if run['tooltool-downloads'] == 'internal':
             taskdesc['scopes'].append(
                 'docker-worker:relengapi-proxy:tooltool.download.internal')
 
     worker['command'] = [
         '/home/worker/bin/run-task',
+        # Various caches/volumes are default owned by root:root.
+        '--chown-recursive', '/home/worker/workspace',
+        '--chown-recursive', '/home/worker/tooltool-cache',
         '--vcs-checkout=/home/worker/workspace/build/src',
         '--',
         'bash',
         '-c',
         'cd /home/worker && '
         './workspace/build/src/taskcluster/scripts/misc/{}'.format(
             run['script'])
     ]