diff --git a/js/about/certerror.js b/js/about/certerror.js
index f5584cc7209..46004f5eeb3 100644
--- a/js/about/certerror.js
+++ b/js/about/certerror.js
@@ -27,6 +27,17 @@ function toByteArray (str) {
   return bytes
 }
 
+function seperateHex (hexStr) {
+  var result = []
+  for (var i = 0; i < hexStr.length; ++i) {
+    result += hexStr[i]
+    if (i % 2 && i != hexStr.length - 1) {
+      result += ':'
+    }
+  }
+  return result
+}
+
 class CertErrorPage extends React.Component {
   constructor () {
     super()
@@ -50,7 +61,7 @@ class CertErrorPage extends React.Component {
         certDetail: true,
         certIssuerName: detail.issuerName,
         certSubjectName: detail.subjectName,
-        certSerialNumber: toHexString(toByteArray(detail.serialNumber)),
+        certSerialNumber: seperateHex(detail.serialNumber),
         certValidStart: validStart.toString(),
         certValidExpiry: validExpiry.toString(),
         certFingerprint: detail.fingerprint.split('/')