diff --git a/.github/workflows/push_subrepos.yml b/.github/workflows/push_subrepos.yml
index 2105ecad..52382283 100644
--- a/.github/workflows/push_subrepos.yml
+++ b/.github/workflows/push_subrepos.yml
@@ -9,6 +9,10 @@ jobs:
     steps:
     - name: Checkout
       uses: actions/checkout@v2
+      with:
+        # fetch full Git history, otherwise push-subrepos.sh would fail due to not being able to
+        # split the git subtree.
+        fetch-depth: 0
     - name: 'Push recent commits to subrepositories'
       env:
         ACCESS_TOKEN: ${{ secrets.HEXOPS_MACH_PUSH_SUBREPOS }}