--- a/taskcluster/ci/desktop-test/tests.yml
+++ b/taskcluster/ci/desktop-test/tests.yml
@@ -173,16 +173,17 @@ jsreftest:
         extra-options:
             - --reftest-suite=jsreftest
 
 marionette:
     description: "Marionette unittest run"
     suite: marionette
     treeherder-symbol: tc(Mn)
     max-run-time: 5400
+    docker-image: {"in-tree": "desktop1604-test"}
     mozharness:
         script: marionette.py
         no-read-buildbot-config: true
         config:
             by-test-platform:
                 win.*:
                     - marionette/windows_taskcluster_config.py
                 default: