diff --git a/src/JsonSchema/Constraints/BaseConstraint.php b/src/JsonSchema/Constraints/BaseConstraint.php
index 336f9fc9..9a4ea1e5 100644
--- a/src/JsonSchema/Constraints/BaseConstraint.php
+++ b/src/JsonSchema/Constraints/BaseConstraint.php
@@ -43,7 +43,7 @@ public function __construct(?Factory $factory = null)
         $this->factory = $factory ?: new Factory();
     }
 
-    public function addError(?JsonPointer $path = null, $message, $constraint = '', array $more = null)
+    public function addError(?JsonPointer $path, $message, $constraint = '', ?array $more = null)
     {
         $error = array(
             'property' => $this->convertJsonPointerIntoPropertyPath($path ?: new JsonPointer('')),
diff --git a/src/JsonSchema/Constraints/Constraint.php b/src/JsonSchema/Constraints/Constraint.php
index 6123dc28..5aaa718c 100644
--- a/src/JsonSchema/Constraints/Constraint.php
+++ b/src/JsonSchema/Constraints/Constraint.php
@@ -39,7 +39,7 @@ abstract class Constraint extends BaseConstraint implements ConstraintInterface
      *
      * @return JsonPointer;
      */
-    protected function incrementPath(?JsonPointer $path = null, $i)
+    protected function incrementPath(?JsonPointer $path, $i)
     {
         $path = $path ?: new JsonPointer('');
 
diff --git a/src/JsonSchema/Constraints/ConstraintInterface.php b/src/JsonSchema/Constraints/ConstraintInterface.php
index 92d1d6c3..a5a235ad 100644
--- a/src/JsonSchema/Constraints/ConstraintInterface.php
+++ b/src/JsonSchema/Constraints/ConstraintInterface.php
@@ -40,7 +40,7 @@ public function addErrors(array $errors);
      * @param string           $constraint the constraint/rule that is broken, e.g.: 'minLength'
      * @param array            $more       more array elements to add to the error
      */
-    public function addError(?JsonPointer $path = null, $message, $constraint='', array $more = null);
+    public function addError(?JsonPointer $path, $message, $constraint='', ?array $more = null);
 
     /**
      * checks if the validator has not raised errors
diff --git a/src/JsonSchema/Constraints/ObjectConstraint.php b/src/JsonSchema/Constraints/ObjectConstraint.php
index 67b54233..e99c44bc 100644
--- a/src/JsonSchema/Constraints/ObjectConstraint.php
+++ b/src/JsonSchema/Constraints/ObjectConstraint.php
@@ -51,7 +51,7 @@ public function check(&$element, $schema = null, ?JsonPointer $path = null, $pro
         $this->validateElement($element, $matches, $schema, $path, $properties, $additionalProp);
     }
 
-    public function validatePatternProperties($element, ?JsonPointer $path = null, $patternProperties)
+    public function validatePatternProperties($element, ?JsonPointer $path, $patternProperties)
     {
         $try = array('/', '#', '+', '~', '%');
         $matches = array();