diff --git a/luhn-algorithm/index.html b/luhn-algorithm/index.html
index 6eab0a3..3ba287b 100644
--- a/luhn-algorithm/index.html
+++ b/luhn-algorithm/index.html
@@ -5,20 +5,20 @@
         <meta http-equiv="X-UA-Compatible" content="IE=edge">
         <meta name="viewport" content="width=device-width, initial-scale=1,minimum-scale=1.0,maximum-scale=1.0,user-scalable=no">
         <meta name="HandheldFriendly" content="True">
-        <link rel="icon" sizes="192x192" href="https://matthew-grove.ml/logo.jpg">
+        <link rel="icon" sizes="192x192" href="https://matthew-grove.ml/logo.png">
 
         <!-- add to homescreen for Chrome on Android -->
         <meta name="mobile-web-app-capable" content="yes">
-        <link rel="icon" sizes="192x192" href="https://matthew-grove.ml/logo.jpg">
+        <link rel="icon" sizes="192x192" href="https://matthew-grove.ml/logo.png">
 
         <!-- add to homescreen for Safari on iOS -->
         <meta name="apple-mobile-web-app-capable" content="yes">
         <meta name="apple-mobile-web-app-status-bar-style" content="black">
         <meta name="apple-mobile-web-app-title" content="Luhn Algorithm | Matthew Grove">
-        <link rel="apple-touch-icon-precomposed" href="https://matthew-grove.ml/logo.jpg">
+        <link rel="apple-touch-icon-precomposed" href="https://matthew-grove.ml/logo.png">
 
         <!-- tile icon & colour for Windows 8 -->
-        <meta name="msapplication-TileImage" content="https://matthew-grove.ml/logo.jpg">
+        <meta name="msapplication-TileImage" content="https://matthew-grove.ml/logo.png">
         <meta name="msapplication-TileColor" content="#d84315">
 
         <title>Luhn Algorithm | Matthew Grove</title>