diff --git a/README.md b/README.md
index b90f3c1..79734e6 100644
--- a/README.md
+++ b/README.md
@@ -8,6 +8,10 @@ A GitHub Action to add labels on PR / Issue events
 
 **Required** Labels to add.
 
+### `issue_number`
+
+**Optional** Issue/Pull number
+
 ## Example usage
 
 ```
diff --git a/index.js b/index.js
index 2852724..313ab6f 100644
--- a/index.js
+++ b/index.js
@@ -15,7 +15,12 @@ const { GitHub, context } = require("@actions/github");
       .getInput("labels")
       .split("\n")
       .filter((x) => x !== "");
-    const issueNumber = context.payload.number;
+    const issueNumber = core.getInput("issue_number", { required: false }) || context.payload.pull_request.number || context.payload.number 
+
+    if (isNaN(issueNumber) || issueNumber < 1) {
+      core.info("no numbers given: skip step");
+      return;
+    }
 
     core.info(`Add labels: ${labels} to ${owner}/${repo}#${issueNumber}`);