diff --git a/lib/clean-host.js b/lib/clean-host.js
index 4a20697..2b69297 100644
--- a/lib/clean-host.js
+++ b/lib/clean-host.js
@@ -66,6 +66,9 @@ function checkLowerCaseNeeded(value) {
 
 
 module.exports = function extractHostname(value) {
+  if (!value || typeof value !== 'string') {
+    return null;
+  }
   // First check if `value` is already a valid hostname.
   if (isValid(value)) {
     return trimTrailingDots(value);
@@ -73,10 +76,6 @@ module.exports = function extractHostname(value) {
 
   var url = value;
 
-  if (typeof url !== 'string') {
-    url = '' + url;
-  }
-
   var needsTrimming = checkTrimmingNeeded(url);
   if (needsTrimming) {
     url = url.trim();