diff --git a/composer.json b/composer.json
index 3f058bbc6..5795eae47 100644
--- a/composer.json
+++ b/composer.json
@@ -11,7 +11,7 @@
         "google/apiclient-services": "~0.13",
         "firebase/php-jwt": "~2.0||~3.0||~4.0||~5.0",
         "monolog/monolog": "^1.17|^2.0",
-        "phpseclib/phpseclib": "~0.3.10||~2.0",
+        "phpseclib/phpseclib": "~0.3.10||~2.0||~3.0",
         "guzzlehttp/guzzle": "~5.3.1||~6.0||~7.0",
         "guzzlehttp/psr7": "^1.2"
     },
diff --git a/src/AccessToken/Verify.php b/src/AccessToken/Verify.php
index 96fabdefd..fadb417ef 100644
--- a/src/AccessToken/Verify.php
+++ b/src/AccessToken/Verify.php
@@ -231,6 +231,10 @@ private function getJwtService()
 
   private function getRsaClass()
   {
+    if (class_exists('phpseclib3\Crypt\RSA')) {
+      return 'phpseclib3\Crypt\RSA';
+    }
+
     if (class_exists('phpseclib\Crypt\RSA')) {
       return 'phpseclib\Crypt\RSA';
     }
@@ -240,6 +244,10 @@ private function getRsaClass()
 
   private function getBigIntClass()
   {
+    if (class_exists('phpseclib3\Math\BigInteger')) {
+      return 'phpseclib3\Math\BigInteger';
+    }
+
     if (class_exists('phpseclib\Math\BigInteger')) {
       return 'phpseclib\Math\BigInteger';
     }
@@ -249,6 +257,10 @@ private function getBigIntClass()
 
   private function getOpenSslConstant()
   {
+    if (class_exists('phpseclib3\Crypt\Common\SymmetricKey')) {
+      return 'hpseclib3\Crypt\Common\SymmetricKey::ENGINE_OPENSSL';
+    }
+
     if (class_exists('phpseclib\Crypt\RSA')) {
       return 'phpseclib\Crypt\RSA::MODE_OPENSSL';
     }
diff --git a/tests/Google/AccessToken/VerifyTest.php b/tests/Google/AccessToken/VerifyTest.php
index bce9501b4..1ffb0e1e1 100644
--- a/tests/Google/AccessToken/VerifyTest.php
+++ b/tests/Google/AccessToken/VerifyTest.php
@@ -139,6 +139,10 @@ private function getJwtService()
 
   private function getOpenSslConstant()
   {
+    if (class_exists('phpseclib3\Crypt\RSA')) {
+      return 'phpseclib3\Crypt\RSA::MODE_OPENSSL';
+    }
+
     if (class_exists('phpseclib\Crypt\RSA')) {
       return 'phpseclib\Crypt\RSA::MODE_OPENSSL';
     }