diff --git a/src/JsonSchema/Constraints/TypeConstraint.php b/src/JsonSchema/Constraints/TypeConstraint.php
index ff4eba71..fe843f70 100644
--- a/src/JsonSchema/Constraints/TypeConstraint.php
+++ b/src/JsonSchema/Constraints/TypeConstraint.php
@@ -81,11 +81,11 @@ public function check(&$value = null, $schema = null, JsonPointer $path = null,
      * of $isValid to true, if at least one $type mateches the type of $value or the value
      * passed as $isValid is already true.
      *
-     * @param mixed $value             Value to validate
-     * @param array $type              TypeConstraints to check against
-     * @param array $validTypesWording An array of wordings of the valid types of the array $type
-     * @param bool  $isValid           The current validation value
-     * @param $path
+     * @param mixed            $value             Value to validate
+     * @param array            $type              TypeConstraints to check against
+     * @param array            $validTypesWording An array of wordings of the valid types of the array $type
+     * @param bool             $isValid           The current validation value
+     * @param JsonPointer|null $path
      */
     protected function validateTypesArray(&$value, array $type, &$validTypesWording, &$isValid, $path, $coerce = false)
     {
@@ -98,21 +98,17 @@ protected function validateTypesArray(&$value, array $type, &$validTypesWording,
             // $tp can be an object, if it's a schema instead of a simple type, validate it
             // with a new type constraint
             if (is_object($tp)) {
-                if (!$isValid) {
-                    $validator = $this->factory->createInstanceFor('type');
-                    $subSchema = new \stdClass();
-                    $subSchema->type = $tp;
-                    $validator->check($value, $subSchema, $path, null);
-                    $error = $validator->getErrors();
-                    $isValid = !(bool) $error;
-                    $validTypesWording[] = self::$wording['object'];
-                }
+                $validator = $this->factory->createInstanceFor('type');
+                $subSchema = new \stdClass();
+                $subSchema->type = $tp;
+                $validator->check($value, $subSchema, $path, null);
+                $error = $validator->getErrors();
+                $isValid = !(bool) $error;
+                $validTypesWording[] = self::$wording['object'];
             } else {
                 $this->validateTypeNameWording($tp);
                 $validTypesWording[] = self::$wording[$tp];
-                if (!$isValid) {
-                    $isValid = $this->validateType($value, $tp, $coerce);
-                }
+                $isValid = $this->validateType($value, $tp, $coerce);
             }
         }
     }
@@ -122,9 +118,9 @@ protected function validateTypesArray(&$value, array $type, &$validTypesWording,
      * difference, that, if $listEnd isn't false, the last element delimiter is $listEnd instead of
      * $delimiter.
      *
-     * @param array  $elements  The elements to implode
-     * @param string $delimiter The delimiter to use
-     * @param bool   $listEnd   The last delimiter to use (defaults to $delimiter)
+     * @param array       $elements  The elements to implode
+     * @param string      $delimiter The delimiter to use
+     * @param bool|string $listEnd   The last delimiter to use (defaults to $delimiter)
      *
      * @return string
      */
@@ -239,7 +235,7 @@ protected function validateType(&$value, $type, $coerce = false)
     /**
      * Converts a value to boolean. For example, "true" becomes true.
      *
-     * @param $value The value to convert to boolean
+     * @param mixed $value The value to convert to boolean
      *
      * @return bool|mixed
      */
diff --git a/src/JsonSchema/Constraints/UndefinedConstraint.php b/src/JsonSchema/Constraints/UndefinedConstraint.php
index bdb95f4a..d4200209 100644
--- a/src/JsonSchema/Constraints/UndefinedConstraint.php
+++ b/src/JsonSchema/Constraints/UndefinedConstraint.php
@@ -140,7 +140,7 @@ protected function validateCommonProperties(&$value, $schema, JsonPointer $path,
                     if (!$this->getTypeCheck()->propertyExists($value, $required)) {
                         $this->addError(
                             ConstraintError::REQUIRED(),
-                            $this->incrementPath($path ?: new JsonPointer(''), $required), array(
+                            $this->incrementPath($path, $required), array(
                                 'property' => $required
                             )
                         );
diff --git a/src/JsonSchema/SchemaStorage.php b/src/JsonSchema/SchemaStorage.php
index 81b3508c..1ec301e3 100644
--- a/src/JsonSchema/SchemaStorage.php
+++ b/src/JsonSchema/SchemaStorage.php
@@ -60,11 +60,25 @@ public function addSchema($id, $schema = null)
         // workaround for bug in draft-03 & draft-04 meta-schemas (id & $ref defined with incorrect format)
         // see https://github.com/json-schema-org/JSON-Schema-Test-Suite/issues/177#issuecomment-293051367
         if (is_object($schema) && property_exists($schema, 'id')) {
-            if ($schema->id == 'http://json-schema.org/draft-04/schema#') {
-                $schema->properties->id->format = 'uri-reference';
-            } elseif ($schema->id == 'http://json-schema.org/draft-03/schema#') {
-                $schema->properties->id->format = 'uri-reference';
-                $schema->properties->{'$ref'}->format = 'uri-reference';
+            $draft03 = false;
+            if (
+                $schema->id === 'http://json-schema.org/draft-04/schema#' ||
+                ($schema->id === 'http://json-schema.org/draft-03/schema#' && $draft03 = true)
+            ) {
+                 if (!property_exists($schema, 'properties')) {
+                     $schema->properties = new \stdClass;
+                 }
+                 if (!property_exists($schema->properties, 'id')) {
+                     $schema->properties->id = new \stdClass;
+                 }
+                 $schema->properties->id->format = 'uri-reference';
+
+                 if ($draft03) {
+                     if (!property_exists($schema->properties, '$ref')) {
+                        $schema->properties->{'$ref'} = new \stdClass;
+                     }
+                     $schema->properties->{'$ref'}->format = 'uri-reference';
+                }
             }
         }
 
diff --git a/tests/SchemaStorageTest.php b/tests/SchemaStorageTest.php
index ebbc9477..9ca7e2c2 100644
--- a/tests/SchemaStorageTest.php
+++ b/tests/SchemaStorageTest.php
@@ -323,4 +323,14 @@ public function testNoDoubleResolve()
             $schemas['test/schema']->{'$ref'}
         );
     }
+
+    public function testAddSchemaMissingProperties()
+    {
+        $schema_03 = array('id' => 'http://json-schema.org/draft-03/schema#');
+        $schema_04 = array('id' => 'http://json-schema.org/draft-04/schema#');
+
+        $s = new SchemaStorage();
+        $s->addSchema($schema_03['id'], $schema_03);
+        $s->addSchema($schema_04['id'], $schema_04);
+    }
 }