diff --git a/.github/workflows/continuous_integration.yml b/.github/workflows/continuous_integration.yml
index 228ca70fd1..4c56a8b465 100644
--- a/.github/workflows/continuous_integration.yml
+++ b/.github/workflows/continuous_integration.yml
@@ -19,6 +19,7 @@ jobs:
           - "7.2"
           - "7.3"
           - "7.4"
+          - "8.0"
 
         dependencies:
           - "highest"
@@ -40,6 +41,9 @@ jobs:
           key: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-${{ hashFiles('**/composer.lock') }}"
           restore-keys: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-"
 
+      - name: "Install composer v1"
+        run: "composer selfupdate --1"
+
       - name: "Install dependencies with composer"
         run: "composer install --no-interaction"
 
diff --git a/composer.json b/composer.json
index 92ccd88b49..e600e15c18 100644
--- a/composer.json
+++ b/composer.json
@@ -32,7 +32,7 @@
         "psr/http-factory": "^1"
     },
     "require-dev": {
-        "phpunit/phpunit": "^8.2.4",
+        "phpunit/phpunit": "^8.2.4||^9.4",
         "php-coveralls/php-coveralls": "^2.1",
         "mouf/picotainer": "^1.1",
         "phpstan/phpstan": "^0.12.25",
diff --git a/src/Mappers/RecursiveTypeMapper.php b/src/Mappers/RecursiveTypeMapper.php
index a53d4d242e..1b5d6715cf 100644
--- a/src/Mappers/RecursiveTypeMapper.php
+++ b/src/Mappers/RecursiveTypeMapper.php
@@ -20,6 +20,7 @@
 use TheCodingMachine\GraphQLite\Types\MutableObjectType;
 use TheCodingMachine\GraphQLite\Types\ObjectFromInterfaceType;
 use TheCodingMachine\GraphQLite\Types\ResolvableMutableInputInterface;
+use TypeError;
 use Webmozart\Assert\Assert;
 use function array_flip;
 use function array_reverse;
@@ -175,7 +176,11 @@ public function findClosestMatchingParent(string $className): ?string
             if ($this->typeMapper->canMapClassToType($className)) {
                 return $className;
             }
-            $className = get_parent_class($className);
+            try {
+                $className = get_parent_class($className);
+            } catch (TypeError $exception) {
+                return null;
+            }
         } while ($className);
 
         return null;
diff --git a/tests/Mappers/CannotMapTypeTraitTest.php b/tests/Mappers/CannotMapTypeTraitTest.php
index 2a1641b175..3eda033f20 100644
--- a/tests/Mappers/CannotMapTypeTraitTest.php
+++ b/tests/Mappers/CannotMapTypeTraitTest.php
@@ -9,8 +9,10 @@
 
 class CannotMapTypeTraitTest extends AbstractQueryProviderTest
 {
-
-    public function testAddParamInfo()
+    /**
+     * @requires PHP <= 7.4
+     */
+    public function testAddParamInfoInfphp80()
     {
         $e = CannotMapTypeException::createForType('Foo');
         $e->addParamInfo((new ReflectionClass('DateTime'))->getMethod('__construct')->getParameters()[0]);
@@ -19,6 +21,18 @@ public function testAddParamInfo()
         $this->assertSame('For parameter $time, in DateTime::__construct, cannot map class "Foo" to a known GraphQL type. Check your TypeMapper configuration.', $e->getMessage());
     }
 
+    /**
+     * @requires PHP >= 8.0
+     */
+    public function testAddParamInfoSupphp74()
+    {
+        $e = CannotMapTypeException::createForType('Foo');
+        $e->addParamInfo((new ReflectionClass('DateTime'))->getMethod('__construct')->getParameters()[0]);
+        $e->addParamInfo((new ReflectionClass('DateTime'))->getMethod('__construct')->getParameters()[0]);
+
+        $this->assertSame('For parameter $datetime, in DateTime::__construct, cannot map class "Foo" to a known GraphQL type. Check your TypeMapper configuration.', $e->getMessage());
+    }
+
     public function testAddSourceFieldInfo()
     {
         $class = new ReflectionClass(TestTypeId::class);