--- a/.taskcluster.yml
+++ b/.taskcluster.yml
@@ -101,18 +101,18 @@ tasks:
               GECKO_HEAD_REPOSITORY: '${repoUrl}'
               GECKO_HEAD_REF: '${push.revision}'
               GECKO_HEAD_REV: '${push.revision}'
               GECKO_COMMIT_MSG: {$if: 'tasks_for != "action"', then: '${push.comment}'}
               HG_STORE_PATH: /builds/worker/checkouts/hg-store
               TASKCLUSTER_CACHES: /builds/worker/checkouts
             - $if: 'tasks_for == "action"'
               then:
-                ACTION_TASK_GROUP_ID: '${ownTaskId}'
-                ACTION_TASK_ID: {$json: {$eval: 'taskId'}}
+                ACTION_TASK_GROUP_ID: '${taskGroupId}'     # taskGroupId of the target task
+                ACTION_TASK_ID: {$json: {$eval: 'taskId'}} # taskId of the target task (JSON-encoded)
                 ACTION_INPUT: {$json: {$eval: 'input'}}
                 ACTION_CALLBACK: '${action.cb_name}'
                 ACTION_PARAMETERS: {$json: {$eval: 'parameters'}}
 
         cache:
           level-${repository.level}-checkouts-sparse-v2: /builds/worker/checkouts
 
         features: