diff --git a/index.js b/index.js
index f7e60399..99f5be2f 100644
--- a/index.js
+++ b/index.js
@@ -6,7 +6,7 @@ const validEvent = ['pull_request'];
 function validateTitlePrefix(title, prefix, caseSensitive) {
     if (!caseSensitive) {
         prefix = prefix.toLowerCase();
-        title = prefix.toLowerCase();
+        title = title.toLowerCase();
     }
     return title.startsWith(prefix);
 }