diff --git a/src/Module/Api/Mastodon/Accounts/UpdateCredentials.php b/src/Module/Api/Mastodon/Accounts/UpdateCredentials.php
index d3f4c15fe0..b2a23cf424 100644
--- a/src/Module/Api/Mastodon/Accounts/UpdateCredentials.php
+++ b/src/Module/Api/Mastodon/Accounts/UpdateCredentials.php
@@ -21,8 +21,9 @@
 
 namespace Friendica\Module\Api\Mastodon\Accounts;
 
+use Friendica\Core\Logger;
 use Friendica\Module\BaseApi;
-use Friendica\Util\Network;
+use Friendica\Util\HTTPInputData;
 
 /**
  * @see https://docs.joinmastodon.org/methods/accounts/
@@ -34,9 +35,10 @@ class UpdateCredentials extends BaseApi
 		self::login(self::SCOPE_WRITE);
 		$uid = self::getCurrentUserID();
 
-		$data = Network::postdata();
+		$data = HTTPInputData::process();
+
+		Logger::info('Patch data', ['data' => $data]);
 
-		// @todo Parse the raw data that is in the "multipart/form-data" format
 		self::unsupported('patch');
 	}
 }
diff --git a/src/Util/HTTPInputData.php b/src/Util/HTTPInputData.php
new file mode 100644
index 0000000000..e3b48cf58d
--- /dev/null
+++ b/src/Util/HTTPInputData.php
@@ -0,0 +1,260 @@
+<?php
+/**
+ * @copyright Copyright (C) 2010-2021, the Friendica project
+ *
+ * @license GNU AGPL version 3 or any later version
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ *
+ */
+
+namespace Friendica\Util;
+
+/**
+ * Derived from the work of Reid Johnson <https://codereview.stackexchange.com/users/4020/reid-johnson>
+ * @see https://codereview.stackexchange.com/questions/69882/parsing-multipart-form-data-in-php-for-put-requests
+ */
+class HTTPInputData
+{
+	public static function process()
+	{
+		$content_parts = explode(';', $_SERVER['CONTENT_TYPE'] ?? 'application/x-www-form-urlencoded');
+
+		$boundary = '';
+		$encoding = '';
+
+		$content_type = array_shift($content_parts);
+
+		foreach ($content_parts as $part) {
+			if (strpos($part, 'boundary') !== false) {
+				$part = explode('=', $part, 2);
+				if (!empty($part[1])) {
+					$boundary = '--' . $part[1];
+				}
+			} elseif (strpos($part, 'charset') !== false) {
+				$part = explode('=', $part, 2);
+				if (!empty($part[1])) {
+					$encoding = $part[1];
+				}
+			}
+			if ($boundary !== '' && $encoding !== '') {
+				break;
+			}
+		}
+
+		if ($content_type == 'multipart/form-data') {
+			return self::fetchFromMultipart($boundary);
+		}
+
+		// can be handled by built in PHP functionality
+		$content = file_get_contents('php://input');
+
+		$variables = json_decode($content);
+
+		if (empty($variables)) {
+			parse_str($content, $variables);
+		}
+
+		return ['variables' => $variables, 'files' => []];
+	}
+
+	private static function fetchFromMultipart(string $boundary)
+	{
+		$result = ['variables' => [], 'files' => []];
+
+		$stream = fopen('php://input', 'rb');
+
+		$sanity = fgets($stream, strlen($boundary) + 5);
+
+		// malformed file, boundary should be first item
+		if (rtrim($sanity) !== $boundary) {
+			return $result;
+		}
+
+		$raw_headers = '';
+
+		while (($chunk = fgets($stream)) !== false) {
+			if ($chunk === $boundary) {
+				continue;
+			}
+
+			if (!empty(trim($chunk))) {
+				$raw_headers .= $chunk;
+				continue;
+			}
+
+			$result = self::parseRawHeader($stream, $raw_headers, $boundary, $result);
+			$raw_headers = '';
+		}
+
+		fclose($stream);
+
+		return $result;
+	}
+
+	private static function parseRawHeader($stream, string $raw_headers, string $boundary, array $result)
+	{
+		$variables = $result['variables'];
+		$files     = $result['files'];
+
+		$headers = [];
+
+		foreach (explode("\r\n", $raw_headers) as $header) {
+			if (strpos($header, ':') === false) {
+				continue;
+			}
+			list($name, $value) = explode(':', $header, 2);
+			$headers[strtolower($name)] = ltrim($value, ' ');
+		}
+
+		if (!isset($headers['content-disposition'])) {
+			return ['variables' => $variables, 'files' => $files];
+		}
+
+		if (!preg_match('/^(.+); *name="([^"]+)"(; *filename="([^"]+)")?/', $headers['content-disposition'], $matches)) {
+			return ['variables' => $variables, 'files' => $files];
+		}
+
+		$name     = $matches[2];
+		$filename = $matches[4] ?? '';
+
+		if (!empty($filename)) {
+			$files[$name] = self::fetchFileData($stream, $boundary, $headers, $filename);
+			return ['variables' => $variables, 'files' => $files];
+		} else {
+			$variables = self::fetchVariables($stream, $boundary, $name, $variables);
+		}
+
+		return ['variables' => $variables, 'files' => $files];
+	}
+
+	private static function fetchFileData($stream, string $boundary, array $headers, string $filename)
+	{
+		$error = UPLOAD_ERR_OK;
+
+		if (isset($headers['content-type'])) {
+			$tmp = explode(';', $headers['content-type']);
+			$contentType = $tmp[0];
+		} else {
+			$contentType = 'unknown';
+		}
+
+		$tmpnam     = tempnam(ini_get('upload_tmp_dir'), 'php');
+		$fileHandle = fopen($tmpnam, 'wb');
+
+		if ($fileHandle === false) {
+			$error = UPLOAD_ERR_CANT_WRITE;
+		} else {
+			$lastLine = NULL;
+			while (($chunk = fgets($stream, 8096)) !== false && strpos($chunk, $boundary) !== 0) {
+				if ($lastLine !== NULL) {
+					if (fwrite($fileHandle, $lastLine) === false) {
+						$error = UPLOAD_ERR_CANT_WRITE;
+						break;
+					}
+				}
+				$lastLine = $chunk;
+			}
+
+			if ($lastLine !== NULL && $error !== UPLOAD_ERR_CANT_WRITE) {
+				if (fwrite($fileHandle, rtrim($lastLine, "\r\n")) === false) {
+					$error = UPLOAD_ERR_CANT_WRITE;
+				}
+			}
+		}
+
+		return [
+			'name'     => $filename,
+			'type'     => $contentType,
+			'tmp_name' => $tmpnam,
+			'error'    => $error,
+			'size'     => filesize($tmpnam)
+		];
+	}
+
+	private static function fetchVariables($stream, string $boundary, string $name, array $variables)
+	{
+		$fullValue = '';
+		$lastLine = NULL;
+
+		while (($chunk = fgets($stream)) !== false && strpos($chunk, $boundary) !== 0) {
+			if ($lastLine !== NULL) {
+				$fullValue .= $lastLine;
+			}
+
+			$lastLine = $chunk;
+		}
+
+		if ($lastLine !== NULL) {
+			$fullValue .= rtrim($lastLine, "\r\n");
+		}
+
+		if (isset($headers['content-type'])) {
+			$encoding = '';
+
+			foreach (explode(';', $headers['content-type']) as $part) {
+				if (strpos($part, 'charset') !== false) {
+					$part = explode($part, '=', 2);
+					if (isset($part[1])) {
+						$encoding = $part[1];
+					}
+					break;
+				}
+			}
+
+			if ($encoding !== '' && strtoupper($encoding) !== 'UTF-8' && strtoupper($encoding) !== 'UTF8') {
+					$tmp = mb_convert_encoding($fullValue, 'UTF-8', $encoding);
+					if ($tmp !== false) {
+						$fullValue = $tmp;
+					}
+			}
+		}
+
+		$fullValue = $name . '=' . $fullValue;
+
+		$tmp = [];
+		parse_str($fullValue, $tmp);
+
+		return self::expandVariables(explode('[', $name), $variables, $tmp);
+	}
+
+	private static function expandVariables(array $names, $variables, array $values)
+	{
+		if (!is_array($variables)) {
+			return $values;
+		}
+
+		$name = rtrim(array_shift($names), ']');
+		if ($name !== '') {
+			$name = $name . '=p';
+
+			$tmp = [];
+			parse_str($name, $tmp);
+
+			$tmp  = array_keys($tmp);
+			$name = reset($tmp);
+		}
+
+		if ($name === '') {
+			$variables[] = reset($values);
+		} elseif (isset($variables[$name]) && isset($values[$name])) {
+			$variables[$name] = self::expandVariables($names, $variables[$name], $values[$name]);
+		} elseif (isset($values[$name])) {
+			$variables[$name] = $values[$name];
+		}
+
+		return $variables;
+	}
+}
+?>