diff --git a/.gitignore b/.gitignore
index eb5a316cbd1..213aa122406 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 target
+*pyc
diff --git a/.taskcluster.yml b/.taskcluster.yml
index 53f8fb86a9d..985e77339e3 100644
--- a/.taskcluster.yml
+++ b/.taskcluster.yml
@@ -21,7 +21,7 @@ tasks:
 
       payload:
         maxRunTime: 600
-        image: "python:2.7.15-stretch"
+        image: "buildpack-deps:bionic-scm"
         features:
           taskclusterProxy: true
         env:
@@ -35,5 +35,4 @@ tasks:
             git clone ${event.repository.clone_url} repo &&
             cd repo &&
             git checkout ${event.after} &&
-            python2.7 -m pip install taskcluster &&
-            python2.7 decision-task.py
+            python2.7 decision-task/run.py
diff --git a/decision-task/requirements.txt b/decision-task/requirements.txt
new file mode 100644
index 00000000000..cbe0ab67c46
--- /dev/null
+++ b/decision-task/requirements.txt
@@ -0,0 +1 @@
+taskcluster==4.0.1
diff --git a/decision-task.py b/decision-task/run.py
similarity index 95%
rename from decision-task.py
rename to decision-task/run.py
index 53c420dd179..736d2dbd582 100644
--- a/decision-task.py
+++ b/decision-task/run.py
@@ -1,6 +1,10 @@
 # coding: utf8
 
 import os
+import sys
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), "vendored"))
+
 import json
 import taskcluster
 
diff --git a/decision-task/vendor.sh b/decision-task/vendor.sh
new file mode 100755
index 00000000000..aaf2bf85254
--- /dev/null
+++ b/decision-task/vendor.sh
@@ -0,0 +1,3 @@
+#!/bin/sh
+cd $(dirname $0)
+python2 -m pip install -r requirements.txt --target vendored