diff --git a/etc/taskcluster/decision_task.py b/etc/taskcluster/decision_task.py
index 7853a84c2f6..3ed715511e5 100644
--- a/etc/taskcluster/decision_task.py
+++ b/etc/taskcluster/decision_task.py
@@ -585,7 +585,7 @@ def update_wpt():
     return (
         linux_task("WPT update")
         .with_treeherder("Linux x64", "WPT update")
-        .with_dockerfile(dockerfile_path("run"))
+        .with_dockerfile(dockerfile_path("wpt-update"))
         .with_features("taskclusterProxy")
         .with_scopes("secrets:get:project/servo/wpt-sync")
         .with_index_and_artifacts_expire_in(log_artifacts_expire_in)
diff --git a/etc/taskcluster/docker/run.dockerfile b/etc/taskcluster/docker/run.dockerfile
index 4be9181f40e..27d67d69b93 100644
--- a/etc/taskcluster/docker/run.dockerfile
+++ b/etc/taskcluster/docker/run.dockerfile
@@ -12,4 +12,4 @@ RUN apt-get install -qy --no-install-recommends \
     libunwind8 \
     #
     # Compiling shaders in OSMesa:
-    llvm \
+    llvm
diff --git a/etc/taskcluster/docker/wpt-update.dockerfile b/etc/taskcluster/docker/wpt-update.dockerfile
new file mode 100644
index 00000000000..0a8edde7bc9
--- /dev/null
+++ b/etc/taskcluster/docker/wpt-update.dockerfile
@@ -0,0 +1,5 @@
+% include run.dockerfile
+
+RUN apt-get install -qy --no-install-recommends \
+    python3 \
+    jq