diff --git a/src/Client.php b/src/Client.php
index 5c27fb1..98f6e26 100644
--- a/src/Client.php
+++ b/src/Client.php
@@ -64,6 +64,13 @@ class Client implements RdapClientInterface, RdapHttpClientAwareInterface
      */
     protected array $protocols = self::PROTOCOLS;
 
+    /**
+     * @var array<string, string> Protocol type aliases, kept for backwards compatibility
+     */
+    private const PROTOCOL_ALIASES = [
+        'ipv46' => self::IPV6,
+    ];
+
     /**
      * @var RequestFactoryInterface|null $requestFactory The PSR-17 request factory
      */
@@ -197,7 +204,7 @@ static function (int $code, string $message) use (&$errorCode, &$errorMessage) :
      */
     public function hasProtocol(string $protocolType) : bool
     {
-        return isset($this->protocols[$protocolType]);
+        return isset($this->protocols[self::PROTOCOL_ALIASES[$protocolType] ?? $protocolType]);
     }
 
     /**
@@ -237,6 +244,7 @@ public function getProtocol(string $protocolType) : RdapProtocolInterface
         ) {
             $protocolType = strtolower(trim($protocolType));
         }
+        $protocolType = self::PROTOCOL_ALIASES[strtolower(trim($protocolType))] ?? $protocolType;
         if (isset($this->protocols[$protocolType])) {
             if (!is_object($this->protocols[$protocolType])) {
                 $this->protocols[$protocolType] = new $this->protocols[$protocolType]($this);
diff --git a/src/Interfaces/RdapClientInterface.php b/src/Interfaces/RdapClientInterface.php
index 34b6e14..421fb45 100644
--- a/src/Interfaces/RdapClientInterface.php
+++ b/src/Interfaces/RdapClientInterface.php
@@ -6,7 +6,7 @@
 interface RdapClientInterface
 {
     public const IPV4 = 'ipv4';
-    public const IPV6 = 'ipv46';
+    public const IPV6 = 'ipv6';
     public const DOMAIN = 'domain';
     public const NS = 'ns';
     public const ASN = 'asn';