diff --git a/tests/bson-serialize-object-persistable-001.phpt b/tests/bson-serialize-object-persistable-001.phpt
index ad9af06..7f768dd 100644
--- a/tests/bson-serialize-object-persistable-001.phpt
+++ b/tests/bson-serialize-object-persistable-001.phpt
@@ -1,5 +1,7 @@
 --TEST--
 BSON serialization: PHP persistable object
+--SKIPIF--
+<?php if (!defined("HHVM_VERSION_ID")) exit("skip PHPC encodes __pclass first"); ?>
 --FILE--
 <?php
 class LiquidClass implements MongoDB\BSON\Persistable
diff --git a/tests/bson-serialize-object-persistable-002.phpt b/tests/bson-serialize-object-persistable-002.phpt
index 09456cb..fcb34b8 100644
--- a/tests/bson-serialize-object-persistable-002.phpt
+++ b/tests/bson-serialize-object-persistable-002.phpt
@@ -1,5 +1,7 @@
 --TEST--
 BSON serialization: PHP persistable object write overwritten __pclass
+--SKIPIF--
+<?php if (!defined("HHVM_VERSION_ID")) exit("skip PHPC encodes __pclass first"); ?>
 --FILE--
 <?php
 class LiquidClass implements MongoDB\BSON\Persistable
diff --git a/tests/bson-serialize-object-serializable-006.phpt b/tests/bson-serialize-object-serializable-006.phpt
index c7a01fc..94a09c9 100644
--- a/tests/bson-serialize-object-serializable-006.phpt
+++ b/tests/bson-serialize-object-serializable-006.phpt
@@ -1,5 +1,7 @@
 --TEST--
 BSON serialization: PHP serializable object: examples from spec
+--SKIPIF--
+<?php if (!defined("HHVM_VERSION_ID")) exit("skip PHPC encodes __pclass first"); ?>
 --FILE--
 <?php
 class MyClass