diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index de1064d8..b5329f76 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -60,10 +60,7 @@ jobs:
           extensions: swoole-4.5.9
           coverage: pcov
           ini-values: pcov.directory=module
-      - if: ${{ matrix.php-version == '8.0' }}
-        run: composer install --no-interaction --prefer-dist --ignore-platform-req=php
-      - if: ${{ matrix.php-version != '8.0' }}
-        run: composer install --no-interaction --prefer-dist
+      - run: composer install --no-interaction --prefer-dist
       - run: composer test:unit:ci
       - uses: actions/upload-artifact@v2
         if: ${{ matrix.php-version == '7.4' }}
@@ -89,10 +86,7 @@ jobs:
           extensions: swoole-4.5.9
           coverage: pcov
           ini-values: pcov.directory=module
-      - if: ${{ matrix.php-version == '8.0' }}
-        run: composer install --no-interaction --prefer-dist --ignore-platform-req=php
-      - if: ${{ matrix.php-version != '8.0' }}
-        run: composer install --no-interaction --prefer-dist
+      - run: composer install --no-interaction --prefer-dist
       - run: composer test:db:sqlite:ci
       - uses: actions/upload-artifact@v2
         if: ${{ matrix.php-version == '7.4' }}
@@ -119,10 +113,7 @@ jobs:
           tools: composer
           extensions: swoole-4.5.9
           coverage: none
-      - if: ${{ matrix.php-version == '8.0' }}
-        run: composer install --no-interaction --prefer-dist --ignore-platform-req=php
-      - if: ${{ matrix.php-version != '8.0' }}
-        run: composer install --no-interaction --prefer-dist
+      - run: composer install --no-interaction --prefer-dist
       - run: composer test:db:mysql
 
   db-tests-maria:
@@ -142,10 +133,7 @@ jobs:
           tools: composer
           extensions: swoole-4.5.9
           coverage: none
-      - if: ${{ matrix.php-version == '8.0' }}
-        run: composer install --no-interaction --prefer-dist --ignore-platform-req=php
-      - if: ${{ matrix.php-version != '8.0' }}
-        run: composer install --no-interaction --prefer-dist
+      - run: composer install --no-interaction --prefer-dist
       - run: composer test:db:maria
 
   db-tests-postgres:
@@ -165,10 +153,7 @@ jobs:
           tools: composer
           extensions: swoole-4.5.9
           coverage: none
-      - if: ${{ matrix.php-version == '8.0' }}
-        run: composer install --no-interaction --prefer-dist --ignore-platform-req=php
-      - if: ${{ matrix.php-version != '8.0' }}
-        run: composer install --no-interaction --prefer-dist
+      - run: composer install --no-interaction --prefer-dist
       - run: composer test:db:postgres
 
   db-tests-ms:
@@ -190,17 +175,13 @@ jobs:
           tools: composer
           extensions: swoole-4.5.9, pdo_sqlsrv-5.9.0beta2
           coverage: none
-      - if: ${{ matrix.php-version == '8.0' }}
-        run: composer install --no-interaction --prefer-dist --ignore-platform-req=php
-      - if: ${{ matrix.php-version != '8.0' }}
-        run: composer install --no-interaction --prefer-dist
+      - run: composer install --no-interaction --prefer-dist
       - name: Create test database
         run: docker-compose exec -T shlink_db_ms /opt/mssql-tools/bin/sqlcmd -S localhost -U sa -P 'Passw0rd!' -Q "CREATE DATABASE shlink_test;"
       - run: composer test:db:ms
 
   api-tests:
     runs-on: ubuntu-20.04
-    continue-on-error: ${{ matrix.php-version == '8.0' }}
     strategy:
       matrix:
         php-version: ['7.4', '8.0']
@@ -217,10 +198,7 @@ jobs:
           extensions: swoole-4.5.9
           coverage: pcov
           ini-values: pcov.directory=module
-      - if: ${{ matrix.php-version == '8.0' }}
-        run: composer install --no-interaction --prefer-dist --ignore-platform-req=php
-      - if: ${{ matrix.php-version != '8.0' }}
-        run: composer install --no-interaction --prefer-dist
+      - run: composer install --no-interaction --prefer-dist
       - run: bin/test/run-api-tests.sh
       - uses: actions/upload-artifact@v2
         if: ${{ matrix.php-version == '7.4' }}
@@ -250,10 +228,7 @@ jobs:
           extensions: swoole-4.5.9
           coverage: pcov
           ini-values: pcov.directory=module
-      - if: ${{ matrix.php-version == '8.0' }}
-        run: composer install --no-interaction --prefer-dist --ignore-platform-req=php
-      - if: ${{ matrix.php-version != '8.0' }}
-        run: composer install --no-interaction --prefer-dist
+      - run: composer install --no-interaction --prefer-dist
       - uses: actions/download-artifact@v2
         with:
           path: build
diff --git a/composer.json b/composer.json
index af175a90..0c397471 100644
--- a/composer.json
+++ b/composer.json
@@ -12,7 +12,7 @@
         }
     ],
     "require": {
-        "php": "^7.4",
+        "php": "^7.4 || ^8.0",
         "ext-json": "*",
         "ext-pdo": "*",
         "akrabat/ip-address-middleware": "^2.0",
@@ -34,10 +34,10 @@
         "lcobucci/jwt": "^4.0",
         "league/uri": "^6.2",
         "lstrojny/functional-php": "^1.15",
-        "mezzio/mezzio": "^3.2",
+        "mezzio/mezzio": "^3.3",
         "mezzio/mezzio-fastroute": "^3.1",
         "mezzio/mezzio-helpers": "^5.3",
-        "mezzio/mezzio-problem-details": "^1.1",
+        "mezzio/mezzio-problem-details": "^1.3",
         "mezzio/mezzio-swoole": "^3.1",
         "monolog/monolog": "^2.0",
         "nikolaposa/monolog-factory": "^3.1",
diff --git a/phpunit-api.xml b/phpunit-api.xml
index b38a3c0f..38a53ca4 100644
--- a/phpunit-api.xml
+++ b/phpunit-api.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <phpunit
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.4/phpunit.xsd"
+    xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
     bootstrap="./config/test/bootstrap_api_tests.php"
     colors="true"
 >
diff --git a/phpunit-db.xml b/phpunit-db.xml
index 030f777b..b2dd8008 100644
--- a/phpunit-db.xml
+++ b/phpunit-db.xml
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <phpunit
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.4/phpunit.xsd"
+    xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
     bootstrap="./config/test/bootstrap_db_tests.php"
     colors="true"
 >
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 9c8e02df..29c60b6b 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,7 +1,7 @@
 <?xml version="1.0"?>
 <phpunit
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:noNamespaceSchemaLocation="https://schema.phpunit.de/9.4/phpunit.xsd"
+    xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
     bootstrap="./vendor/autoload.php"
     colors="true"
 >