diff --git a/.github/workflows/pr-title.yml b/.github/workflows/pr-title.yml
new file mode 100644
index 00000000..b89795d7
--- /dev/null
+++ b/.github/workflows/pr-title.yml
@@ -0,0 +1,52 @@
+name: "Validate PR title"
+
+on:
+  pull_request_target:
+    types:
+      - opened
+      - edited
+      - synchronize
+
+jobs:
+  main:
+    name: Validate PR title
+    runs-on: ubuntu-latest
+    steps:
+      # Please look up the latest version from
+      # https://github.com/amannn/action-semantic-pull-request/releases
+      - uses: amannn/action-semantic-pull-request@v3.4.6
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        with:
+          # Configure which types are allowed.
+          # Default: https://github.com/commitizen/conventional-commit-types
+          types: |
+            fix
+            feat
+            docs
+            ci
+            chore
+          # Configure that a scope must always be provided.
+          requireScope: false
+          # Configure additional validation for the subject based on a regex.
+          # This example ensures the subject starts with an uppercase character.
+          subjectPattern: ^[A-Z].+$
+          # If `subjectPattern` is configured, you can use this property to override
+          # the default error message that is shown when the pattern doesn't match.
+          # The variables `subject` and `title` can be used within the message.
+          subjectPatternError: |
+            The subject "{subject}" found in the pull request title "{title}"
+            didn't match the configured pattern. Please ensure that the subject
+            starts with an uppercase character.
+          # For work-in-progress PRs you can typically use draft pull requests
+          # from Github. However, private repositories on the free plan don't have
+          # this option and therefore this action allows you to opt-in to using the
+          # special "[WIP]" prefix to indicate this state. This will avoid the
+          # validation of the PR title and the pull request checks remain pending.
+          # Note that a second check will be reported if this is enabled.
+          wip: true
+          # When using "Squash and merge" on a PR with only one commit, GitHub
+          # will suggest using that commit message instead of the PR title for the
+          # merge commit, and it's easy to commit this by mistake. Enable this option
+          # to also validate the commit message for one commit PRs.
+          validateSingleCommit: false
diff --git a/README.md b/README.md
index 87a4fd64..a4e05397 100644
--- a/README.md
+++ b/README.md
@@ -139,6 +139,7 @@ See the [functions](https://github.com/terraform-aws-modules/terraform-aws-notif
 | <a name="output_notify_slack_lambda_function_name"></a> [notify\_slack\_lambda\_function\_name](#output\_notify\_slack\_lambda\_function\_name) | The name of the Lambda function |
 | <a name="output_notify_slack_lambda_function_version"></a> [notify\_slack\_lambda\_function\_version](#output\_notify\_slack\_lambda\_function\_version) | Latest published version of your Lambda function |
 | <a name="output_slack_topic_arn"></a> [slack\_topic\_arn](#output\_slack\_topic\_arn) | The ARN of the SNS topic from which messages will be sent to Slack |
+| <a name="output_this_slack_topic_arn"></a> [this\_slack\_topic\_arn](#output\_this\_slack\_topic\_arn) | The ARN of the SNS topic from which messages will be sent to Slack (backward compatibility for version 4.x) |
 <!-- END OF PRE-COMMIT-TERRAFORM DOCS HOOK -->
 
 ## Authors
diff --git a/outputs.tf b/outputs.tf
index 000ef549..762c8328 100644
--- a/outputs.tf
+++ b/outputs.tf
@@ -3,6 +3,12 @@ output "slack_topic_arn" {
   value       = local.sns_topic_arn
 }
 
+# todo: Remove `this_slack_topic_arn` output during next major release 5.x
+output "this_slack_topic_arn" {
+  description = "The ARN of the SNS topic from which messages will be sent to Slack (backward compatibility for version 4.x)"
+  value       = local.sns_topic_arn
+}
+
 output "lambda_iam_role_arn" {
   description = "The ARN of the IAM role used by Lambda function"
   value       = module.lambda.lambda_role_arn