diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e299c734..a06f052f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -4,11 +4,21 @@ permissions:
   contents: read
   id-token: write
 
-on: [pull_request, workflow_call]
+on:
+  pull_request:
+  workflow_call:
+    inputs:
+      branch:
+        description: "Branch to checkout"
+        required: false
+        default: master
+        type: string
 
 jobs:
   shared-ci:
     uses: ./.github/workflows/shared-ci.yml
+    with:
+      branch: ${{ inputs.branch || 'master' }}
   pr-ci-all-required:
     if: always()
     needs:
diff --git a/.github/workflows/daily_ci.yml b/.github/workflows/daily_ci.yml
index f0f56257..9eb7d08f 100644
--- a/.github/workflows/daily_ci.yml
+++ b/.github/workflows/daily_ci.yml
@@ -15,7 +15,12 @@ jobs:
   DAILY_CI:
     # Don't run the cron builds on forks
     if: github.event_name != 'schedule' || github.repository_owner == 'aws'
+    strategy:
+      matrix:
+        branch: [master, v4.x]
     uses: ./.github/workflows/ci.yml
+    with:
+      branch: ${{ matrix.branch }}
   notify:
     needs:
       [
diff --git a/.github/workflows/shared-ci.yml b/.github/workflows/shared-ci.yml
index 88233a59..045c5e55 100644
--- a/.github/workflows/shared-ci.yml
+++ b/.github/workflows/shared-ci.yml
@@ -3,6 +3,11 @@ name: Shared CI Tests
 on:
   workflow_call:
     inputs:
+      branch:
+        description: "Branch to checkout"
+        required: false
+        default: master
+        type: string
       test-published-packages:
         description: 'Test against published packages instead of checked out code'
         required: false
@@ -34,6 +39,7 @@ jobs:
         # Always need repo for test scripts and configuration, even when testing published packages
         uses: actions/checkout@v4
         with:
+          ref: ${{ inputs.branch }}
           fetch-depth: 0
           submodules: true