--- a/.taskcluster.yml
+++ b/.taskcluster.yml
@@ -61,21 +61,23 @@ tasks:
         - "index.gecko.v2.{{project}}.latest.firefox.decision"
         - "tc-treeherder.v2.{{project}}.{{revision}}.{{pushlog_id}}"
         - "tc-treeherder-stage.v2.{{project}}.{{revision}}.{{pushlog_id}}"
 
       payload:
         env:
           # checkout-gecko uses these to check out the source; the inputs
           # to `mach taskgraph decision` are all on the command line.
-          GECKO_BASE_REPOSITORY: 'https://hg.mozilla.org/mozilla-central'
+          GECKO_BASE_REPOSITORY: 'https://hg.mozilla.org/mozilla-unified'
           GECKO_HEAD_REPOSITORY: '{{{url}}}'
           GECKO_HEAD_REF: '{{revision}}'
           GECKO_HEAD_REV: '{{revision}}'
           # Arguments passed into `mach taskgraph decision`
+          # TODO use mozilla-unified for the base repository once the tc-vcs
+          # tar.gz archives are created or tc-vcs isn't being used.
           DECISION_ARGS: >
             --pushlog-id='{{pushlog_id}}'
             --project='{{project}}'
             --message='{{comment}}'
             --owner='{{owner}}'
             --level='{{level}}'
             --base-repository='https://hg.mozilla.org/mozilla-central'
             --head-repository='{{{url}}}'

--- a/taskcluster/taskgraph/action.yml
+++ b/taskcluster/taskgraph/action.yml
@@ -22,17 +22,17 @@ scopes:
   - "assume:repo:hg.mozilla.org/try:*"
 
 routes:
   - "tc-treeherder.v2.{{project}}.{{head_rev}}.{{pushlog_id}}"
   - "tc-treeherder-stage.v2.{{project}}.{{head_rev}}.{{pushlog_id}}"
 
 payload:
   env:
-    GECKO_BASE_REPOSITORY: 'https://hg.mozilla.org/mozilla-central'
+    GECKO_BASE_REPOSITORY: 'https://hg.mozilla.org/mozilla-unified'
     GECKO_HEAD_REPOSITORY: '{{{head_repository}}}'
     GECKO_HEAD_REF: '{{head_ref}}'
     GECKO_HEAD_REV: '{{head_rev}}'
     ACTION_ARGS: >
       --decision-id='{{decision_task_id}}'
       --task-labels='{{task_labels}}'
 
   cache: