diff --git a/taskcluster/kinds/source-test/python.yml b/taskcluster/kinds/source-test/python.yml
index f0b964d28414..0fe0e5eac23b 100644
--- a/taskcluster/kinds/source-test/python.yml
+++ b/taskcluster/kinds/source-test/python.yml
@@ -49,6 +49,7 @@ firefox-ci:
             - '.taskcluster.yml'
             - 'taskcluster/kinds/**'
             - 'taskcluster/**/*.py'
+            - 'third_party/python/taskcluster_taskgraph/**/*.py'
             - 'tools/tryselect/selectors/auto.py'
 
 fog:
@@ -343,8 +344,9 @@ taskgraph-tests:
         subsuite: taskgraph
     when:
         files-changed:
-            - 'taskcluster/**/*.py'
             - 'python/mach/**/*.py'
+            - 'taskcluster/**/*.py'
+            - 'third_party/python/taskcluster_taskgraph/**/*.py'
 
 tryselect:
     description: tools/tryselect unit tests
@@ -362,6 +364,7 @@ tryselect:
             - 'taskcluster/config.yml'
             - 'taskcluster/kinds/test/**'
             - 'taskcluster/gecko_taskgraph/transforms/**'
+            - 'third_party/python/taskcluster_taskgraph/**/*.py'
             - 'tools/tryselect/**'
 
 mozbuild:
diff --git a/taskcluster/kinds/source-test/taskgraph.yml b/taskcluster/kinds/source-test/taskgraph.yml
index da3b27d33b11..e930df106b84 100644
--- a/taskcluster/kinds/source-test/taskgraph.yml
+++ b/taskcluster/kinds/source-test/taskgraph.yml
@@ -40,3 +40,4 @@ diff:
         files-changed:
             - 'taskcluster/kinds/**'
             - 'taskcluster/**/*.py'
+            - 'third_party/python/taskcluster_taskgraph/**/*.py'