diff --git a/send.go b/send.go
index 8e00ec7..f38c23b 100644
--- a/send.go
+++ b/send.go
@@ -36,7 +36,7 @@ const (
 
 // Known Workflow URL patterns for submitting messages to Microsoft Teams.
 const (
-	WorkflowURLBaseDomain = `^https:\/\/(?:.*\.azure-api|logic\.azure)\.(?:com|net)`
+	WorkflowURLBaseDomain = `^https:\/\/(?:.*)(:?\.azure-api|logic\.azure)\.(?:com|net)`
 )
 
 // DisableWebhookURLValidation is a special keyword used to indicate to