diff --git a/.github/workflows/sync-translations-fa.yml b/.github/workflows/sync-translations-fa.yml
index b5629555..46324a79 100644
--- a/.github/workflows/sync-translations-fa.yml
+++ b/.github/workflows/sync-translations-fa.yml
@@ -6,6 +6,10 @@ name: Sync Translations (Farsi)
 on:
   pull_request:
     types: [closed]
+    # Only merges into main sync. Without this, a PR merged into any branch
+    # (a long-lived migration branch, say) opens translation PRs for content
+    # the published edition does not carry.
+    branches: [main]
     paths:
       - 'lectures/**/*.md'
       - 'lectures/_toc.yml'
diff --git a/.github/workflows/sync-translations-fr.yml b/.github/workflows/sync-translations-fr.yml
index e8fc8bdd..fa8a83da 100644
--- a/.github/workflows/sync-translations-fr.yml
+++ b/.github/workflows/sync-translations-fr.yml
@@ -6,6 +6,10 @@ name: Sync Translations (French)
 on:
   pull_request:
     types: [closed]
+    # Only merges into main sync. Without this, a PR merged into any branch
+    # (a long-lived migration branch, say) opens translation PRs for content
+    # the published edition does not carry.
+    branches: [main]
     paths:
       - 'lectures/**/*.md'
       - 'lectures/_toc.yml'
diff --git a/.github/workflows/sync-translations-zh-cn.yml b/.github/workflows/sync-translations-zh-cn.yml
index 9296d879..ee0604ed 100644
--- a/.github/workflows/sync-translations-zh-cn.yml
+++ b/.github/workflows/sync-translations-zh-cn.yml
@@ -6,6 +6,10 @@ name: Sync Translations (Simplified Chinese)
 on:
   pull_request:
     types: [closed]
+    # Only merges into main sync. Without this, a PR merged into any branch
+    # (a long-lived migration branch, say) opens translation PRs for content
+    # the published edition does not carry.
+    branches: [main]
     paths:
       - 'lectures/**/*.md'
       - 'lectures/_toc.yml'