diff --git a/.php_cs.dist b/.php_cs.dist
index 5a7a578e..a9e7e4ed 100644
--- a/.php_cs.dist
+++ b/.php_cs.dist
@@ -26,6 +26,7 @@ $config
         'trailing_comma_in_multiline_array' => false,
         'yoda_style' => false,
         'phpdoc_types_order' => array('null_adjustment' => 'none', 'sort_algorithm' => 'none'),
+        'no_superfluous_phpdoc_tags' => false,
     ))
     ->setFinder($finder)
 ;
diff --git a/.travis.yml b/.travis.yml
index 0573330b..ca5eced3 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -28,6 +28,7 @@ matrix:
       dist: trusty
   allow_failures:
     - php: nightly
+    - php: hhvm-3.18
 
 before_install:
   - if [[ "$WITH_COVERAGE" != "true" && "$TRAVIS_PHP_VERSION" != "hhvm-3.18" && "$TRAVIS_PHP_VERSION" != "nightly" && "$TRAVIS_PHP_VERSION" != "7.1" ]]; then phpenv config-rm xdebug.ini; fi
diff --git a/src/JsonSchema/Constraints/Constraint.php b/src/JsonSchema/Constraints/Constraint.php
index a53130df..c61b89ad 100644
--- a/src/JsonSchema/Constraints/Constraint.php
+++ b/src/JsonSchema/Constraints/Constraint.php
@@ -42,10 +42,15 @@ abstract class Constraint extends BaseConstraint implements ConstraintInterface
     protected function incrementPath(JsonPointer $path = null, $i)
     {
         $path = $path ?: new JsonPointer('');
+
+        if ($i === null || $i === '') {
+            return $path;
+        }
+
         $path = $path->withPropertyPaths(
             array_merge(
                 $path->getPropertyPaths(),
-                array_filter(array($i), 'strlen')
+                array($i)
             )
         );