diff --git a/build.gradle b/build.gradle
index 136b914..dcb56b4 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,5 +1,5 @@
 plugins {
-    id 'org.jetbrains.kotlin.jvm' version '1.3.20'
+    id 'org.jetbrains.kotlin.jvm' version '1.5.21'
 }
 
 group 'uk.co.pittendreigh'