diff --git a/composer.json b/composer.json
index a0064df2..4cf5e77d 100644
--- a/composer.json
+++ b/composer.json
@@ -82,7 +82,7 @@
         "dompdf/dompdf": "^1.0",
         "friendsofphp/php-cs-fixer": "^3.2",
         "jpgraph/jpgraph": "^4.0",
-        "mpdf/mpdf": "8.0.17",
+        "mpdf/mpdf": "8.1.1",
         "phpcompatibility/php-compatibility": "^9.3",
         "phpstan/phpstan": "^1.1",
         "phpstan/phpstan-phpunit": "^1.0",
diff --git a/composer.lock b/composer.lock
index 37bab549..ce00e3e5 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "ed42c40a4281d97171980367f24d0a25",
+    "content-hash": "2e09b120ad90fc0fbbc055e1f341910e",
     "packages": [
         {
             "name": "ezyang/htmlpurifier",
@@ -1302,16 +1302,16 @@
         },
         {
             "name": "mpdf/mpdf",
-            "version": "v8.0.17",
+            "version": "v8.1.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/mpdf/mpdf.git",
-                "reference": "5f64118317c8145c0abc606b310aa0a66808398a"
+                "reference": "e511e89a66bdb066e3fbf352f00f4734d5064cbf"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/mpdf/mpdf/zipball/5f64118317c8145c0abc606b310aa0a66808398a",
-                "reference": "5f64118317c8145c0abc606b310aa0a66808398a",
+                "url": "https://api.github.com/repos/mpdf/mpdf/zipball/e511e89a66bdb066e3fbf352f00f4734d5064cbf",
+                "reference": "e511e89a66bdb066e3fbf352f00f4734d5064cbf",
                 "shasum": ""
             },
             "require": {
@@ -1320,6 +1320,8 @@
                 "myclabs/deep-copy": "^1.7",
                 "paragonie/random_compat": "^1.4|^2.0|^9.99.99",
                 "php": "^5.6 || ^7.0 || ~8.0.0 || ~8.1.0",
+                "php-http/message-factory": "^1.0",
+                "psr/http-message": "^1.0",
                 "psr/log": "^1.0 || ^2.0",
                 "setasign/fpdi": "^2.1"
             },
@@ -1373,7 +1375,7 @@
                     "type": "custom"
                 }
             ],
-            "time": "2022-01-20T10:51:40+00:00"
+            "time": "2022-04-18T11:50:28+00:00"
         },
         {
             "name": "myclabs/deep-copy",
@@ -1793,6 +1795,60 @@
             },
             "time": "2020-10-14T08:32:19+00:00"
         },
+        {
+            "name": "php-http/message-factory",
+            "version": "v1.0.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/php-http/message-factory.git",
+                "reference": "a478cb11f66a6ac48d8954216cfed9aa06a501a1"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/php-http/message-factory/zipball/a478cb11f66a6ac48d8954216cfed9aa06a501a1",
+                "reference": "a478cb11f66a6ac48d8954216cfed9aa06a501a1",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.4",
+                "psr/http-message": "^1.0"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.0-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Http\\Message\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Márk Sági-Kazár",
+                    "email": "mark.sagikazar@gmail.com"
+                }
+            ],
+            "description": "Factory interfaces for PSR-7 HTTP Message",
+            "homepage": "http://php-http.org",
+            "keywords": [
+                "factory",
+                "http",
+                "message",
+                "stream",
+                "uri"
+            ],
+            "support": {
+                "issues": "https://github.com/php-http/message-factory/issues",
+                "source": "https://github.com/php-http/message-factory/tree/master"
+            },
+            "time": "2015-12-19T14:08:53+00:00"
+        },
         {
             "name": "phpcompatibility/php-compatibility",
             "version": "9.3.5",