diff --git a/boot.php b/boot.php
index e1c5733704..b45bc57670 100644
--- a/boot.php
+++ b/boot.php
@@ -835,28 +835,6 @@ function check_addons(App $a)
 	return;
 }
 
-function get_guid($size = 16, $prefix = '')
-{
-	if (is_bool($prefix) && !$prefix) {
-		$prefix = '';
-	} elseif ($prefix == '') {
-		$a = get_app();
-		$prefix = hash('crc32', $a->get_hostname());
-	}
-
-	while (strlen($prefix) < ($size - 13)) {
-		$prefix .= mt_rand();
-	}
-
-	if ($size >= 24) {
-		$prefix = substr($prefix, 0, $size - 22);
-		return str_replace('.', '', uniqid($prefix, true));
-	} else {
-		$prefix = substr($prefix, 0, max($size - 13, 0));
-		return uniqid($prefix);
-	}
-}
-
 /**
  * @brief Used to end the current process, after saving session state.
  * @deprecated
diff --git a/include/api.php b/include/api.php
index 42868aa9eb..dd8daa9e66 100644
--- a/include/api.php
+++ b/include/api.php
@@ -4534,7 +4534,7 @@ function post_photo_item($hash, $allow_cid, $deny_cid, $allow_gid, $deny_gid, $f
 	$owner_record = q("SELECT * FROM `contact` WHERE `uid`= %d AND `self` LIMIT 1", intval(api_user()));
 
 	$arr = [];
-	$arr['guid']          = get_guid(32);
+	$arr['guid']          = System::createGUID(32);
 	$arr['uid']           = intval(api_user());
 	$arr['uri']           = $uri;
 	$arr['parent-uri']    = $uri;
diff --git a/include/text.php b/include/text.php
index 0066e18814..0957d92d73 100644
--- a/include/text.php
+++ b/include/text.php
@@ -1549,7 +1549,7 @@ function return_bytes($size_str) {
 function generate_user_guid() {
 	$found = true;
 	do {
-		$guid = get_guid(32);
+		$guid = System::createGUID(32);
 		$x = q("SELECT `uid` FROM `user` WHERE `guid` = '%s' LIMIT 1",
 			dbesc($guid)
 		);
diff --git a/mod/item.php b/mod/item.php
index a6a3a50c80..4e27a80cf6 100644
--- a/mod/item.php
+++ b/mod/item.php
@@ -232,7 +232,7 @@ function item_post(App $a) {
 		$emailcc           =      notags(trim(defaults($_REQUEST, 'emailcc' , '')));
 		$body              = escape_tags(trim(defaults($_REQUEST, 'body'    , '')));
 		$network           =      notags(trim(defaults($_REQUEST, 'network' , NETWORK_DFRN)));
-		$guid              = get_guid(32);
+		$guid              =      System::createGUID(32);
 
 		$postopts = defaults($_REQUEST, 'postopts', '');
 
diff --git a/mod/photos.php b/mod/photos.php
index 34eea0c642..d969fd3271 100644
--- a/mod/photos.php
+++ b/mod/photos.php
@@ -453,7 +453,7 @@ function photos_post(App $a)
 			$uri = Item::newURI($page_owner_uid);
 
 			$arr = [];
-			$arr['guid']          = get_guid(32);
+			$arr['guid']          = System::createGUID(32);
 			$arr['uid']           = $page_owner_uid;
 			$arr['uri']           = $uri;
 			$arr['parent-uri']    = $uri;
@@ -620,7 +620,7 @@ function photos_post(App $a)
 					$uri = Item::newURI($page_owner_uid);
 
 					$arr = [];
-					$arr['guid']          = get_guid(32);
+					$arr['guid']          = System::createGUID(32);
 					$arr['uid']           = $page_owner_uid;
 					$arr['uri']           = $uri;
 					$arr['parent-uri']    = $uri;
@@ -856,7 +856,7 @@ function photos_post(App $a)
 		$arr['coord'] = $lat . ' ' . $lon;
 	}
 
-	$arr['guid']          = get_guid(32);
+	$arr['guid']          = System::createGUID(32);
 	$arr['uid']           = $page_owner_uid;
 	$arr['uri']           = $uri;
 	$arr['parent-uri']    = $uri;
diff --git a/mod/poke.php b/mod/poke.php
index 55bb799d1f..2fd7068f78 100644
--- a/mod/poke.php
+++ b/mod/poke.php
@@ -96,7 +96,7 @@ function poke_init(App $a) {
 
 	$arr = [];
 
-	$arr['guid']          = get_guid(32);
+	$arr['guid']          = System::createGUID(32);
 	$arr['uid']           = $uid;
 	$arr['uri']           = $uri;
 	$arr['parent-uri']    = ($parent_uri ? $parent_uri : $uri);
diff --git a/mod/proxy.php b/mod/proxy.php
index 0b84233e5f..ca8ced3cd6 100644
--- a/mod/proxy.php
+++ b/mod/proxy.php
@@ -188,7 +188,7 @@ function proxy_init(App $a) {
 				die();
 			}
 
-			$fields = ['uid' => 0, 'contact-id' => 0, 'guid' => get_guid(), 'resource-id' => $urlhash, 'created' => DateTimeFormat::utcNow(), 'edited' => DateTimeFormat::utcNow(),
+			$fields = ['uid' => 0, 'contact-id' => 0, 'guid' => System::createGUID(), 'resource-id' => $urlhash, 'created' => DateTimeFormat::utcNow(), 'edited' => DateTimeFormat::utcNow(),
 				'filename' => basename($_REQUEST['url']), 'type' => '', 'album' => '', 'height' => imagesy($image), 'width' => imagesx($image),
 				'datasize' => 0, 'data' => $img_str, 'scale' => 100, 'profile' => 0,
 				'allow_cid' => '', 'allow_gid' => '', 'deny_cid' => '', 'deny_gid' => '', 'desc' => $mime];
diff --git a/mod/subthread.php b/mod/subthread.php
index e05aa5fec8..a624cd9a60 100644
--- a/mod/subthread.php
+++ b/mod/subthread.php
@@ -118,7 +118,7 @@ EOT;
 
 	$arr = [];
 
-	$arr['guid'] = get_guid(32);
+	$arr['guid'] = System::createGUID(32);
 	$arr['uri'] = $uri;
 	$arr['uid'] = $owner_uid;
 	$arr['contact-id'] = $contact['id'];
diff --git a/mod/tagger.php b/mod/tagger.php
index 717c094776..0df31ac9a3 100644
--- a/mod/tagger.php
+++ b/mod/tagger.php
@@ -115,7 +115,7 @@ EOT;
 
 	$arr = [];
 
-	$arr['guid'] = get_guid(32);
+	$arr['guid'] = System::createGUID(32);
 	$arr['uri'] = $uri;
 	$arr['uid'] = $owner_uid;
 	$arr['contact-id'] = $contact['id'];
diff --git a/mod/wall_attach.php b/mod/wall_attach.php
index 07092cf180..29c790843a 100644
--- a/mod/wall_attach.php
+++ b/mod/wall_attach.php
@@ -6,6 +6,7 @@
 use Friendica\App;
 use Friendica\Core\Config;
 use Friendica\Core\L10n;
+use Friendica\Core\System;
 use Friendica\Database\DBM;
 use Friendica\Util\DateTimeFormat;
 use Friendica\Util\Mimetype;
@@ -121,7 +122,7 @@ function wall_attach_post(App $a) {
 
 	$filedata = @file_get_contents($src);
 	$mimetype = Mimetype::getContentType($filename);
-	$hash = get_guid(64);
+	$hash = System::createGUID(64);
 	$created = DateTimeFormat::utcNow();
 
 	$fields = ['uid' => $page_owner_uid, 'hash' => $hash, 'filename' => $filename, 'filetype' => $mimetype,
diff --git a/src/Core/System.php b/src/Core/System.php
index 84a64ab9a8..46d1b34e55 100644
--- a/src/Core/System.php
+++ b/src/Core/System.php
@@ -175,9 +175,36 @@ EOT;
 		killme();
 	}
 
+	/**
+	 * Generates a GUID with the given parameters
+	 *
+	 * @param int          $size     The size of the GUID (default is 16)
+	 * @param bool|string  $prefix   A given prefix (default is empty)
+	 * @return string a generated GUID
+	 */
+	public static function createGUID($size = 16, $prefix = '')
+	{
+		if (is_bool($prefix) && !$prefix) {
+			$prefix = '';
+		} elseif (empty($prefix)) {
+			$prefix = hash('crc32', self::getApp()->get_hostname());
+		}
+
+		while (strlen($prefix) < ($size - 13)) {
+			$prefix .= mt_rand();
+		}
+
+		if ($size >= 24) {
+			$prefix = substr($prefix, 0, $size - 22);
+			return str_replace('.', '', uniqid($prefix, true));
+		} else {
+			$prefix = substr($prefix, 0, max($size - 13, 0));
+			return uniqid($prefix);
+		}
+	}
+
 	/// @todo Move the following functions from boot.php
 	/*
-	function get_guid($size = 16, $prefix = "")
 	function killme()
 	function goaway($s)
 	function local_user()
diff --git a/src/Model/Event.php b/src/Model/Event.php
index 49d759585a..66d5f389fe 100644
--- a/src/Model/Event.php
+++ b/src/Model/Event.php
@@ -305,7 +305,7 @@ class Event extends BaseObject
 
 			Addon::callHooks('event_updated', $event['id']);
 		} else {
-			$event['guid'] = get_guid(32);
+			$event['guid'] = System::createGUID(32);
 
 			// New event. Store it.
 			dba::insert('event', $event);
diff --git a/src/Model/Item.php b/src/Model/Item.php
index f10c20936a..c077331728 100644
--- a/src/Model/Item.php
+++ b/src/Model/Item.php
@@ -1075,7 +1075,7 @@ class Item extends BaseObject
 		} elseif (!empty($item['uri'])) {
 			$guid = self::guidFromUri($item['uri'], $prefix_host);
 		} else {
-			$guid = get_guid(32, hash('crc32', $prefix_host));
+			$guid = System::createGUID(32, hash('crc32', $prefix_host));
 		}
 
 		return $guid;
@@ -2172,7 +2172,7 @@ class Item extends BaseObject
 	public static function newURI($uid, $guid = "")
 	{
 		if ($guid == "") {
-			$guid = get_guid(32);
+			$guid = System::createGUID(32);
 		}
 
 		$hostname = self::getApp()->get_hostname();
@@ -2496,7 +2496,7 @@ class Item extends BaseObject
 			}
 
 			if ($contact['network'] != NETWORK_FEED) {
-				$datarray["guid"] = get_guid(32);
+				$datarray["guid"] = System::createGUID(32);
 				unset($datarray["plink"]);
 				$datarray["uri"] = self::newURI($contact['uid'], $datarray["guid"]);
 				$datarray["parent-uri"] = $datarray["uri"];
@@ -2933,7 +2933,7 @@ class Item extends BaseObject
 		$objtype = $item['resource-id'] ? ACTIVITY_OBJ_IMAGE : ACTIVITY_OBJ_NOTE ;
 
 		$new_item = [
-			'guid'          => get_guid(32),
+			'guid'          => System::createGUID(32),
 			'uri'           => self::newURI($item['uid']),
 			'uid'           => $item['uid'],
 			'contact-id'    => $item_contact_id,
diff --git a/src/Model/Mail.php b/src/Model/Mail.php
index 81494e7ebb..f10ad368ba 100644
--- a/src/Model/Mail.php
+++ b/src/Model/Mail.php
@@ -47,7 +47,7 @@ class Mail
 			return -2;
 		}
 
-		$guid = get_guid(32);
+		$guid = System::createGUID(32);
 		$uri = 'urn:X-dfrn:' . System::baseUrl() . ':' . local_user() . ':' . $guid;
 
 		$convid = 0;
@@ -76,7 +76,7 @@ class Mail
 			$recip_handle = (($contact['addr']) ? $contact['addr'] : $contact['nick'] . '@' . $recip_host);
 			$sender_handle = $a->user['nickname'] . '@' . substr(System::baseUrl(), strpos(System::baseUrl(), '://') + 3);
 
-			$conv_guid = get_guid(32);
+			$conv_guid = System::createGUID(32);
 			$convuri = $recip_handle . ':' . $conv_guid;
 
 			$handles = $recip_handle . ';' . $sender_handle;
@@ -174,7 +174,7 @@ class Mail
 			$subject = L10n::t('[no subject]');
 		}
 
-		$guid = get_guid(32);
+		$guid = System::createGUID(32);
 		$uri = 'urn:X-dfrn:' . System::baseUrl() . ':' . local_user() . ':' . $guid;
 
 		$me = Probe::uri($replyto);
@@ -183,7 +183,7 @@ class Mail
 			return -2;
 		}
 
-		$conv_guid = get_guid(32);
+		$conv_guid = System::createGUID(32);
 
 		$recip_handle = $recipient['nickname'] . '@' . substr(System::baseUrl(), strpos(System::baseUrl(), '://') + 3);
 
diff --git a/src/Model/Photo.php b/src/Model/Photo.php
index c622421cc0..b08c6f0459 100644
--- a/src/Model/Photo.php
+++ b/src/Model/Photo.php
@@ -45,7 +45,7 @@ class Photo
 		if (DBM::is_result($photo)) {
 			$guid = $photo['guid'];
 		} else {
-			$guid = get_guid();
+			$guid = System::createGUID();
 		}
 
 		$existing_photo = dba::selectFirst('photo', ['id'], ['resource-id' => $rid, 'uid' => $uid, 'contact-id' => $cid, 'scale' => $scale]);
@@ -275,6 +275,6 @@ class Photo
 	 */
 	public static function newResource()
 	{
-		return get_guid(32, false);
+		return system::createGUID(32, false);
 	}
 }
diff --git a/src/Protocol/Diaspora.php b/src/Protocol/Diaspora.php
index 2ce54317eb..ccd825d4e1 100644
--- a/src/Protocol/Diaspora.php
+++ b/src/Protocol/Diaspora.php
@@ -3220,7 +3220,7 @@ class Diaspora
 		$author = self::myHandle($owner);
 
 		$message = ["author" => $author,
-				"guid" => get_guid(32),
+				"guid" => System::createGUID(32),
 				"parent_type" => "Post",
 				"parent_guid" => $item["guid"]];
 
diff --git a/tests/src/Core/SystemTest.php b/tests/src/Core/SystemTest.php
new file mode 100644
index 0000000000..b85bce44cb
--- /dev/null
+++ b/tests/src/Core/SystemTest.php
@@ -0,0 +1,37 @@
+<?php
+
+namespace Friendica\Test\src\Core;
+
+use Friendica\Core\System;
+use PHPUnit\Framework\TestCase;
+
+class SystemTest extends TestCase
+{
+	private function assertGuid($guid, $length, $prefix = '')
+	{
+		print $guid;
+		$length -= strlen($prefix);
+		$this->assertRegExp("/^" . $prefix . "[a-z0-9]{" . $length . "}?$/", $guid);
+	}
+
+	function testGuidWithoutParameter()
+	{
+		$guid = System::createGUID();
+		$this->assertGuid($guid, 16);
+	}
+
+	function testGuidWithSize32() {
+		$guid = System::createGUID(32);
+		$this->assertGuid($guid, 32);
+	}
+
+	function testGuidWithSize64() {
+		$guid = System::createGUID(64);
+		$this->assertGuid($guid, 64);
+	}
+
+	function testGuidWithPrefix() {
+		$guid = System::createGUID(23, 'test');
+		$this->assertGuid($guid, 23, 'test');
+	}
+}
\ No newline at end of file