diff --git a/phpBB/includes/functions_user.php b/phpBB/includes/functions_user.php
index a408f695aa..f3867d4cd2 100644
--- a/phpBB/includes/functions_user.php
+++ b/phpBB/includes/functions_user.php
@@ -1026,7 +1026,8 @@ function user_ipwhois($ip)
 	$match = array();
 
 	// Test for referrals from $whois_host to other whois databases, roll on rwhois
-	if (preg_match('#ReferralServer:[\x20]*whois://(.+)#im', $ipwhois, $match))
+	// Search for referral servers with or without the "whois://" prefix
+	if (preg_match('#ReferralServer:[\x20]*whois://(.+)#im', $ipwhois, $match) || preg_match('#ReferralServer:[\x20]*([^/]+)$#im', $ipwhois, $match))
 	{
 		if (strpos($match[1], ':') !== false)
 		{
diff --git a/tests/functions_user/whois_test.php b/tests/functions_user/whois_test.php
index 26793802d5..5dfe6f4930 100644
--- a/tests/functions_user/whois_test.php
+++ b/tests/functions_user/whois_test.php
@@ -33,8 +33,10 @@ class phpbb_functions_user_whois_test extends phpbb_test_case
 	public static function ips_data()
 	{
 		return [
-			['2001:4860:4860::8888'], // Google public DNS
-			['64.233.161.139'], // google.com
+			['2001:4860:4860::8888'], // Google public DNS (ARIN)
+			['64.233.161.139'], // google.com (ARIN)
+			['1.1.1.1'], // Cloudflare (APNIC via whois:// referral)
+			['213.133.116.44'], // Hetzner (RIPE via non-whois:// referral)
 		];
 	}
 
@@ -47,5 +49,6 @@ class phpbb_functions_user_whois_test extends phpbb_test_case
 		$this->assertStringNotContainsString('Query terms are ambiguous', $ip_whois);
 		$this->assertStringNotContainsString('no entries found', $ip_whois);
 		$this->assertStringNotContainsString('ERROR', $ip_whois);
+		$this->assertStringNotContainsString('Allocated to RIPE NCC', $ip_whois); // This only shows if the referral isn't found
 	}
 }