diff --git a/.github/workflows/block-needs-review.yml b/.github/workflows/block-needs-review.yml
new file mode 100644
index 000000000..014120500
--- /dev/null
+++ b/.github/workflows/block-needs-review.yml
@@ -0,0 +1,12 @@
+name: Block needs-review merges
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened, labeled, unlabeled]
+
+permissions:
+  pull-requests: read
+
+jobs:
+  gate:
+    uses: awslabs/aws-crt-builder/.github/workflows/block-needs-review-label.yml@main
diff --git a/.github/workflows/check-abi.yml b/.github/workflows/check-abi.yml
new file mode 100644
index 000000000..ab3b882b2
--- /dev/null
+++ b/.github/workflows/check-abi.yml
@@ -0,0 +1,43 @@
+name: Check ABI compliance
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+concurrency:
+  group: check-abi-${{ github.event.pull_request.number }}
+  cancel-in-progress: true
+
+env:
+  PACKAGE_NAME: aws-c-s3
+  CRT_CI_ROLE: ${{ secrets.CRT_CI_ROLE_ARN }}
+  AWS_DEFAULT_REGION: us-east-1
+
+permissions:
+  id-token: write
+  contents: read
+  pull-requests: write
+
+jobs:
+  check-abi:
+    name: check-abi
+    runs-on: ubuntu-24.04
+    steps:
+      - uses: aws-actions/configure-aws-credentials@v4
+        with:
+          role-to-assume: ${{ env.CRT_CI_ROLE }}
+          aws-region: ${{ env.AWS_DEFAULT_REGION }}
+
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Check ABI
+        # Pointing at the fork branch while the builder change is in review.
+        # Switch to awslabs/aws-crt-builder/.github/actions/check-abi@main once merged.
+        uses: awslabs/aws-crt-builder/.github/actions/check-abi@main
+        with:
+          lib-name: ${{ env.PACKAGE_NAME }}
+          builder-version: latest
+          builder-source: releases
diff --git a/include/aws/s3/private/s3_client_impl.h b/include/aws/s3/private/s3_client_impl.h
index a3388fc8e..17fb8e4fd 100644
--- a/include/aws/s3/private/s3_client_impl.h
+++ b/include/aws/s3/private/s3_client_impl.h
@@ -215,6 +215,8 @@ struct aws_s3_upload_part_timeout_stats {
 struct aws_s3_client {
     struct aws_allocator *allocator;
 
+    int random_new_member;
+
     struct aws_s3_buffer_pool *buffer_pool;
 
     struct aws_s3_client_vtable *vtable;