diff --git a/.patches/custom-itip-broker.diff b/.patches/custom-itip-broker.diff
new file mode 100644
index 000000000..13c835816
--- /dev/null
+++ b/.patches/custom-itip-broker.diff
@@ -0,0 +1,52 @@
+diff --git a/lib/CalDAV/Schedule/Plugin.php b/lib/CalDAV/Schedule/Plugin.php
+index 5e56596101..5bca56d47e 100644
+--- a/lib/CalDAV/Schedule/Plugin.php
++++ b/lib/CalDAV/Schedule/Plugin.php
+@@ -25,6 +25,7 @@
+ use Sabre\VObject;
+ use Sabre\VObject\Component\VCalendar;
+ use Sabre\VObject\ITip;
++use Sabre\VObject\ITip\Broker;
+ use Sabre\VObject\ITip\Message;
+ use Sabre\VObject\Reader;
+ 
+@@ -389,7 +390,7 @@ public function beforeUnbind($path)
+             $node->getOwner()
+         );
+ 
+-        $broker = new ITip\Broker();
++        $broker = $this->createITipBroker();
+         $messages = $broker->parseEvent(null, $addresses, $node->get());
+ 
+         foreach ($messages as $message) {
+@@ -500,7 +501,7 @@ public function scheduleLocalDelivery(ITip\Message $iTipMessage)
+             $isNewNode = true;
+         }
+ 
+-        $broker = new ITip\Broker();
++        $broker = $this->createITipBroker();
+         $newObject = $broker->processMessage($iTipMessage, $currentObject);
+ 
+         $inbox->createFile($newFileName, $iTipMessage->message->serialize());
+@@ -611,7 +612,7 @@ public function getSupportedPrivilegeSet(INode $node, array &$supportedPrivilege
+      */
+     protected function processICalendarChange($oldObject, VCalendar $newObject, array $addresses, array $ignore = [], &$modified = false)
+     {
+-        $broker = new ITip\Broker();
++        $broker = $this->createITipBroker();
+         $messages = $broker->parseEvent($newObject, $addresses, $oldObject);
+ 
+         if ($messages) {
+@@ -994,4 +995,12 @@ public function getPluginInfo()
+             'link' => 'http://sabre.io/dav/scheduling/',
+         ];
+     }
++
++    /**
++     * Returns an instance of the iTip\Broker.
++     */
++    protected function createITipBroker(): Broker
++    {
++        return new Broker();
++    }
+ }
diff --git a/composer.patches.json b/composer.patches.json
index 96a4fa1ea..b86d16fd9 100644
--- a/composer.patches.json
+++ b/composer.patches.json
@@ -1,6 +1,7 @@
 {
 	"patches": {
 		"sabre/dav": {
+			"Allow for custom iTip broker": ".patches/custom-itip-broker.diff",
 			"Fix getNodeForPath cache": ".patches/fix-cache-for-node.diff"
 		},
 		"wapmorgan/mp3info": {
diff --git a/composer/installed.json b/composer/installed.json
index c86ca1583..9ba0c1d2e 100644
--- a/composer/installed.json
+++ b/composer/installed.json
@@ -3683,6 +3683,7 @@
             "type": "library",
             "extra": {
                 "patches_applied": {
+                    "Allow for custom iTip broker": ".patches/custom-itip-broker.diff",
                     "Fix getNodeForPath cache": ".patches/fix-cache-for-node.diff"
                 }
             },
diff --git a/composer/installed.php b/composer/installed.php
index a9110ae04..123b89dab 100644
--- a/composer/installed.php
+++ b/composer/installed.php
@@ -3,7 +3,7 @@
         'name' => 'nextcloud/3rdparty',
         'pretty_version' => 'dev-master',
         'version' => 'dev-master',
-        'reference' => NULL,
+        'reference' => null,
         'type' => 'library',
         'install_path' => __DIR__ . '/../',
         'aliases' => array(),
@@ -292,7 +292,7 @@
         'nextcloud/3rdparty' => array(
             'pretty_version' => 'dev-master',
             'version' => 'dev-master',
-            'reference' => NULL,
+            'reference' => null,
             'type' => 'library',
             'install_path' => __DIR__ . '/../',
             'aliases' => array(),
diff --git a/sabre/dav/PATCHES.txt b/sabre/dav/PATCHES.txt
index 9e202eda2..101f21ee6 100644
--- a/sabre/dav/PATCHES.txt
+++ b/sabre/dav/PATCHES.txt
@@ -1,6 +1,10 @@
 This file was automatically generated by Composer Patches (https://github.com/cweagans/composer-patches)
 Patches applied to this directory:
 
+Allow for custom iTip broker
+Source: .patches/custom-itip-broker.diff
+
+
 Fix getNodeForPath cache
 Source: .patches/fix-cache-for-node.diff
 
diff --git a/sabre/dav/lib/CalDAV/Schedule/Plugin.php b/sabre/dav/lib/CalDAV/Schedule/Plugin.php
index 5e5659610..5bca56d47 100644
--- a/sabre/dav/lib/CalDAV/Schedule/Plugin.php
+++ b/sabre/dav/lib/CalDAV/Schedule/Plugin.php
@@ -25,6 +25,7 @@
 use Sabre\VObject;
 use Sabre\VObject\Component\VCalendar;
 use Sabre\VObject\ITip;
+use Sabre\VObject\ITip\Broker;
 use Sabre\VObject\ITip\Message;
 use Sabre\VObject\Reader;
 
@@ -389,7 +390,7 @@ public function beforeUnbind($path)
             $node->getOwner()
         );
 
-        $broker = new ITip\Broker();
+        $broker = $this->createITipBroker();
         $messages = $broker->parseEvent(null, $addresses, $node->get());
 
         foreach ($messages as $message) {
@@ -500,7 +501,7 @@ public function scheduleLocalDelivery(ITip\Message $iTipMessage)
             $isNewNode = true;
         }
 
-        $broker = new ITip\Broker();
+        $broker = $this->createITipBroker();
         $newObject = $broker->processMessage($iTipMessage, $currentObject);
 
         $inbox->createFile($newFileName, $iTipMessage->message->serialize());
@@ -611,7 +612,7 @@ public function getSupportedPrivilegeSet(INode $node, array &$supportedPrivilege
      */
     protected function processICalendarChange($oldObject, VCalendar $newObject, array $addresses, array $ignore = [], &$modified = false)
     {
-        $broker = new ITip\Broker();
+        $broker = $this->createITipBroker();
         $messages = $broker->parseEvent($newObject, $addresses, $oldObject);
 
         if ($messages) {
@@ -994,4 +995,12 @@ public function getPluginInfo()
             'link' => 'http://sabre.io/dav/scheduling/',
         ];
     }
+
+    /**
+     * Returns an instance of the iTip\Broker.
+     */
+    protected function createITipBroker(): Broker
+    {
+        return new Broker();
+    }
 }