diff --git a/src/Utils.php b/src/Utils.php
index f52d502..ef76657 100644
--- a/src/Utils.php
+++ b/src/Utils.php
@@ -15,8 +15,8 @@ class Utils
     public static function parseJwt($jwt)
     {
         $tokenParts = explode('.', $jwt);
-        $header = json_decode(base64_decode($tokenParts[0]), true);
-        $payload = json_decode(base64_decode($tokenParts[1]), true);
+        $header = json_decode(self::base64url_decode($tokenParts[0]), true);
+        $payload = json_decode(self::base64url_decode($tokenParts[1]), true);
 
         return ['header' => $header, 'payload' => $payload];
     }
@@ -28,11 +28,11 @@ public static function parseJwt($jwt)
      */
     public static function generateJwt($headers, $payload, $key)
     {
-        $encodedHeaders = self::base64urlEncode(json_encode($headers));
-        $encodedPayload = self::base64urlEncode(json_encode($payload));
+        $encodedHeaders = self::base64url_encode(json_encode($headers));
+        $encodedPayload = self::base64url_encode(json_encode($payload));
 
         $signature = hash_hmac('SHA256', "$encodedHeaders.$encodedPayload", $key, true);
-        $encodedSignature = self::base64urlEncode($signature);
+        $encodedSignature = self::base64url_encode($signature);
 
         return "$encodedHeaders.$encodedPayload.$encodedSignature";
     }
@@ -51,21 +51,27 @@ public static function isJwtValid($jwt, $timeFn, $key)
         $tokenSignature = $tokenParts[2];
 
         // check the expiration time - note this will cause an error if there is no 'exp' claim in the jwt
-        $expiration = json_decode(base64_decode($payload))->exp;
+        $expiration = json_decode(self::base64url_decode($payload))->exp;
         $isTokenExpired = $expiration <= $timeFn();
 
         // build a signature based on the header and payload using the secret
         $signature = hash_hmac('SHA256', $header.'.'.$payload, $key, true);
-        $isSignatureValid = self::base64urlEncode($signature) === $tokenSignature;
+        $isSignatureValid = self::base64url_encode($signature) === $tokenSignature;
 
         return $isSignatureValid && ! $isTokenExpired;
     }
 
-    public static function base64urlEncode($str)
+    public static function base64url_encode($str): string
     {
         return rtrim(strtr(base64_encode($str), '+/', '-_'), '=');
     }
 
+    /**
+     * https://www.php.net/manual/en/function.base64-encode.php#127544
+     */
+    public static function base64url_decode($data) {
+        return base64_decode(strtr($data, '-_', '+/'), true);
+    }
 
     const SOCKET_ID_ERROR = "please make sure to send base64 encoded json with "
     ."'connectionKey' and 'clientId' as keys. 'clientId' is null if connection is not identified";
@@ -76,10 +82,9 @@ public static function base64urlEncode($str)
     public static function decodeSocketId($socketId) {
         $socketIdObject = null;
         if ($socketId) {
-            try {
-                $socketIdObject = json_decode(base64_decode($socketId));
-            } catch (\Exception $e) {
-                throw new AblyException("SocketId decoding failed, ".self::SOCKET_ID_ERROR, 0, $e);
+            $socketIdObject = json_decode(self::base64url_decode($socketId));
+            if (!$socketIdObject) {
+                throw new AblyException("SocketId decoding failed, ".self::SOCKET_ID_ERROR);
             }
             if (!isset($socketIdObject->connectionKey)) {
                 throw new AblyException("ConnectionKey is missing, ".self::SOCKET_ID_ERROR);
diff --git a/tests/UtilsTest.php b/tests/UtilsTest.php
index 975462b..bdb6ad1 100644
--- a/tests/UtilsTest.php
+++ b/tests/UtilsTest.php
@@ -26,4 +26,13 @@ public function testGenerateAndValidateToken()
         $jwtIsValid = Utils::isJwtValid($jwtToken, $timeFn, 'efgh');
         self::assertTrue($jwtIsValid);
     }
+
+    public function testValidateDecodingSocketId() {
+        $socketId = new \stdClass();
+        $socketId->connectionKey = 'key';
+        $socketId->clientId = 'clientId';
+        $socketIdObject = Utils::decodeSocketId(Utils::base64url_encode(json_encode($socketId)));
+        self::assertEquals('key', $socketIdObject->connectionKey);
+        self::assertEquals('clientId', $socketIdObject->clientId);
+    }
 }