diff --git a/.github/ensure-builder/action.yml b/.github/ensure-builder/action.yml
index 753c2e6b6ec..ab2a9e95d39 100644
--- a/.github/ensure-builder/action.yml
+++ b/.github/ensure-builder/action.yml
@@ -69,21 +69,24 @@ runs:
     # Set up a context for this run
     - name: Copy Repo to Builder
       shell: bash
+      env:
+        UNPACK: |
+          [ -d ~/run-$RUN_ID ] || (
+            mkdir -p ~/run-$RUN_ID-git &&
+            cd ~/run-$RUN_ID-git && tar xzf - &&
+            git config --global advice.detachedHead false &&
+            git clone ~/run-$RUN_ID-git/.git ~/run-$RUN_ID &&
+            echo ${{ env.BUILD_INSTANCE_SSH_KEY }} | base64 --decode > ~/.ssh/build_instance_key &&
+            chmod 600 ~/.ssh/build_instance_key
+          )
       run: |
         sudo shutdown -P ${{ steps.select_instance.outputs.ttl }}
         set -x
         # detect run folder
         if ! scripts/run_on_builder "[ -d ~/run-$RUN_ID ]" ; then
           echo "Copying local repo to spot"
-          tar czf - .git | scripts/run_on_builder \
-            "mkdir -p ~/run-$RUN_ID-git && cd ~/run-$RUN_ID-git && tar xzf -" || true
-          scripts/run_on_builder "
-            echo "Unpacking repo"
-            git config --global advice.detachedHead false
-            git clone ~/run-$RUN_ID-git/.git ~/run-$RUN_ID
-            echo ${{ env.BUILD_INSTANCE_SSH_KEY }} | base64 --decode > ~/.ssh/build_instance_key
-            chmod 600 ~/.ssh/build_instance_key
-          " || true
+          (tar czf - .git || true) | scripts/run_on_builder \
+            "flock ~/git.lock bash -c '$UNPACK'"
         fi
 
     - name: Attach EBS Cache Disk
diff --git a/yarn-project/README.md b/yarn-project/README.md
index 9c4c5010812..11437af9c9d 100644
--- a/yarn-project/README.md
+++ b/yarn-project/README.md
@@ -48,7 +48,7 @@ Consider installing the Prettier and ESLint extensions if using VSCode. Configur
 
 ## Package.json inheritance
 
-To simplify the management of all package.json files, we have a custom script that injects the contents of `package.common.json` into all packages that reference it via the `inherits` custom field. To run the script, just run
+To simplify the management of all package.json files, we have a custom script that injects the contents of `package.common.json` into all packages that reference it via the `inherits` custom field. To run the script, just run:
 
 ```
 yarn prepare