diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 568363b1..3a6802f1 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -14,7 +14,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        action: [report, done]  # Note: We're also testing 'install' since it's implicitly in each of these two actions
+        action: [report, done, build-number-report, build-number-done]  # Note: We're also testing 'install' since it's implicit in each action
         fail_on_error: [true, false]
     steps:
       - name: Checkout code
@@ -36,13 +36,14 @@ jobs:
         run: |
           echo "Running on Windows"
 
-      - name: Run Test Action
+      - name: Test Action
         uses: ./
         with:
           github-token: ${{ secrets.GITHUB_TOKEN }}
           fail-on-error: ${{ matrix.fail_on_error }}
           debug: true
-          parallel-finished: ${{ matrix.action == 'done' }}  # Only set 'parallel-finished' to true when testing 'done'
+          build-number: ${{ (matrix.action == 'build-number-report' || matrix.action == 'build-number-done') && github.sha || '' }} # Only set 'build-number' to `${{ github.sha }}` when testing `build-number-report` or `build-number-done`
+          parallel-finished: ${{ matrix.action == 'done' || matrix.action == 'build-number-done' }}  # Only set `parallel-finished` to `true` when testing `done` or `build-number-done`
         env:
           CI: true
         continue-on-error: ${{ matrix.fail_on_error }}
diff --git a/action.yml b/action.yml
index ab37dc7f..e9032638 100644
--- a/action.yml
+++ b/action.yml
@@ -22,6 +22,9 @@ inputs:
   flag-name:
     description: 'Job flag name, e.g. "Unit", "Functional", or "Integration". Will be shown in the Coveralls UI.'
     required: false
+  build-number:
+    description: 'Override the build number autodetected from CI. This is useful if your CI tool assigns a different build number per each parallel build.'
+    required: false
   parallel:
     description: 'Set to true if you are running parallel jobs, then use "parallel-finished: true" for the last action.'
     required: false
@@ -195,6 +198,7 @@ runs:
         coveralls done
         ${{ inputs.debug == 'true' && '--debug' || '' }}
         ${{ inputs.measure == 'true' && '--measure' || '' }}
+        ${{ inputs.build-number && format('--build-number {0}', inputs.build-number) || '' }}
         ${{ inputs.fail-on-error == 'false' && '--no-fail' || '' }}
       env:
         COVERALLS_DEBUG: ${{ inputs.debug }}
@@ -216,6 +220,7 @@ runs:
         ${{ inputs.fail-on-error == 'false' && '--no-fail' || '' }}
         ${{ inputs.allow-empty == 'true' && '--allow-empty' || '' }}
         ${{ inputs.base-path && format('--base-path {0}', inputs.base-path) || '' }}
+        ${{ inputs.build-number && format('--build-number {0}', inputs.build-number) || '' }}
         ${{ inputs.format && format('--format {0}', inputs.format) || '' }}
         ${{ inputs.file || inputs.path-to-lcov }}
         ${{ inputs.files }}