diff --git a/src/wp-includes/http.php b/src/wp-includes/http.php
index 05792c29c2..dc750371ac 100644
--- a/src/wp-includes/http.php
+++ b/src/wp-includes/http.php
@@ -523,7 +523,7 @@ function wp_http_validate_url( $url ) {
 
 	$parsed_home = @parse_url( get_option( 'home' ) );
 
-	if ( isset( $parsed_home['host'] ) ) { 
+	if ( isset( $parsed_home['host'] ) ) {
 		$same_host = ( strtolower( $parsed_home['host'] ) === strtolower( $parsed_url['host'] ) || 'localhost' === strtolower( $parsed_url['host'] ) );
 	} else {
 		$same_host = false;
@@ -531,7 +531,7 @@ function wp_http_validate_url( $url ) {
 
 	if ( ! $same_host ) {
 		$host = trim( $parsed_url['host'], '.' );
-		if ( preg_match( '#^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$#', $host ) ) {
+		if ( preg_match( '#^(([1-9]?\d|1\d\d|25[0-5]|2[0-4]\d)\.){3}([1-9]?\d|1\d\d|25[0-5]|2[0-4]\d)$#', $host ) ) {
 			$ip = $host;
 		} else {
 			$ip = gethostbyname( $host );