diff --git a/composer.json b/composer.json
index 466a747..b492c91 100644
--- a/composer.json
+++ b/composer.json
@@ -17,7 +17,7 @@
     "php": ">=7.2.0",
     "ext-json": "*",
     "ext-openssl": "*",
-    "phpseclib/phpseclib": "^2.0"
+    "phpseclib/phpseclib": "^3.0"
   },
   "autoload": {
     "psr-4": {
diff --git a/src/KeyConverter.php b/src/KeyConverter.php
index 1bdff2d..ad7dc4d 100644
--- a/src/KeyConverter.php
+++ b/src/KeyConverter.php
@@ -4,8 +4,9 @@
 
 namespace Strobotti\JWK;
 
-use phpseclib\Crypt\RSA;
-use phpseclib\Math\BigInteger;
+use phpseclib3\Crypt\RSA\PublicKey;
+use phpseclib3\Crypt\PublicKeyLoader;
+use phpseclib3\Math\BigInteger;
 use Strobotti\JWK\Key\KeyInterface;
 use Strobotti\JWK\Key\Rsa as RsaKey;
 use Strobotti\JWK\Util\Base64UrlConverter;
@@ -42,16 +43,14 @@ public function keyToPem(KeyInterface $key): string
             throw new \InvalidArgumentException();
         }
 
-        /** @var RsaKey $key */
-        $rsa = new RSA();
-
         $modulus = $this->base64UrlConverter->decode($key->getModulus(), true);
 
-        $rsa->loadKey([
+        /** @var PublicKey $loader */
+        $loader = PublicKeyLoader::load([
             'e' => new BigInteger(\base64_decode($key->getExponent(), true), 256),
             'n' => new BigInteger($modulus, 256),
         ]);
 
-        return $rsa->getPublicKey();
+        return $loader->toString('PKCS8');
     }
 }