diff --git a/ModelDescriber/Annotations/SymfonyConstraintAnnotationReader.php b/ModelDescriber/Annotations/SymfonyConstraintAnnotationReader.php
index 4f392ef..dfd10c2 100644
--- a/ModelDescriber/Annotations/SymfonyConstraintAnnotationReader.php
+++ b/ModelDescriber/Annotations/SymfonyConstraintAnnotationReader.php
@@ -49,7 +49,7 @@ class SymfonyConstraintAnnotationReader
         foreach ($annotations as $annotation) {
             if ($annotation instanceof Assert\NotBlank || $annotation instanceof Assert\NotNull) {
                 // To support symfony/validator < 4.3
-                if ($annotation instanceof Assert\NotBlank && \method_exists($annotation, 'allowNull') && $annotation->allowNull) {
+                if ($annotation instanceof Assert\NotBlank && \property_exists($annotation, 'allowNull') && $annotation->allowNull) {
                     // The field is optional
                     continue;
                 }
diff --git a/Tests/ModelDescriber/Annotations/SymfonyConstraintAnnotationReaderTest.php b/Tests/ModelDescriber/Annotations/SymfonyConstraintAnnotationReaderTest.php
index a7e5827..fd1b245 100644
--- a/Tests/ModelDescriber/Annotations/SymfonyConstraintAnnotationReaderTest.php
+++ b/Tests/ModelDescriber/Annotations/SymfonyConstraintAnnotationReaderTest.php
@@ -49,7 +49,7 @@ class SymfonyConstraintAnnotationReaderTest extends TestCase
 
     public function testOptionalProperty()
     {
-        if (!\method_exists(Assert\NotBlank::class, 'allowNull')) {
+        if (!\property_exists(Assert\NotBlank::class, 'allowNull')) {
             $this->markTestSkipped('NotBlank::allowNull was added in symfony/validator 4.3.');
         }