diff --git a/index.js b/index.js
index ef0e890..16dce00 100644
--- a/index.js
+++ b/index.js
@@ -46,7 +46,7 @@ Toolkit.run(async tools => {
       milestone: tools.inputs.milestone || attributes.milestone
     })
 
-    core.setOutput('number', issue.data.number)
+    core.setOutput('number', String(issue.data.number))
     core.setOutput('url', issue.data.html_url)
     tools.log.success(`Created issue ${issue.data.title}#${issue.data.number}: ${issue.data.html_url}`)
   } catch (err) {
diff --git a/tests/index.test.js b/tests/index.test.js
index bfecc70..a147430 100644
--- a/tests/index.test.js
+++ b/tests/index.test.js
@@ -54,7 +54,7 @@ describe('create-an-issue', () => {
     // Verify that the outputs were set
     expect(core.setOutput).toHaveBeenCalledTimes(2)
     expect(core.setOutput).toHaveBeenCalledWith('url', 'www')
-    expect(core.setOutput).toHaveBeenCalledWith('number', 1)
+    expect(core.setOutput).toHaveBeenCalledWith('number', '1')
   })
 
   it('creates a new issue from a different template', async () => {