diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 75fc9de139..30db034b94 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -545,3 +545,8 @@ jobs:
           gh workflow -R leanprover/release-index run update-index.yml
         env:
           GITHUB_TOKEN: ${{ secrets.RELEASE_INDEX_TOKEN }}
+      - name: Update toolchain on mathlib4's nightly-testing branch
+        run: |
+          gh workflow -R leanprover-community/mathlib4 run nightly_bump_toolchain.yml
+        env:
+          GITHUB_TOKEN: ${{ secrets.MATHLIB4_BOT }}