diff --git a/playground-spring-boot-autoconfigure/src/main/resources/templates/playground.html b/playground-spring-boot-autoconfigure/src/main/resources/templates/playground.html
index be52603b..b7586ce9 100644
--- a/playground-spring-boot-autoconfigure/src/main/resources/templates/playground.html
+++ b/playground-spring-boot-autoconfigure/src/main/resources/templates/playground.html
@@ -2,7 +2,7 @@
 <html>
 
 <head>
-    <meta charset=utf-8/>
+    <meta charset="utf-8"/>
     <meta name="viewport" content="user-scalable=no, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, minimal-ui">
     <title th:text="${pageTitle}"></title>
     <link rel="stylesheet" th:href="${cssUrl}" />
