diff --git a/.gitignore b/.gitignore
index 3e04db63..fb4082bb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1,5 @@
 vendor/
+*.hhast.parser-cache
 *.swp
 *~
 composer.lock
diff --git a/src/lies_we_tell_hack.hhi b/src/lies_we_tell_hack.hhi
deleted file mode 100644
index 97016d0f..00000000
--- a/src/lies_we_tell_hack.hhi
+++ /dev/null
@@ -1,21 +0,0 @@
-<?hh // strict
-/*
- *  Copyright (c) 2004-present, Facebook, Inc.
- *  All rights reserved.
- *
- *  This source code is licensed under the MIT license found in the
- *  LICENSE file in the root directory of this source tree.
- *
- */
-
-namespace HH {
-  class InvariantException extends \InvariantException {} // @oss-enable
-  type KeyedContainer<Tk, Tv> = \KeyedContainer<Tk, Tv>;
-}
-
-namespace {
-  const POSIX_S_IFMT = 0;
-  const POSIX_S_IFREG = 0;
-  const POSIX_S_IFDIR = 0;
-  const POSIX_S_IFLNK = 0;
-}
diff --git a/tests/regex/RegexTest.php b/tests/regex/RegexTest.php
index 9ff8b172..4f562d09 100644
--- a/tests/regex/RegexTest.php
+++ b/tests/regex/RegexTest.php
@@ -13,7 +13,6 @@
 
 use function Facebook\FBExpect\expect; // @oss-enable
 use type Facebook\HackTest\{DataProvider, HackTest}; // @oss-enable
-use type HH\InvariantException as InvariantViolationException; // @oss-enable
 
 // @oss-disable: <<Oncalls('hack')>>
 final class RegexTest extends HackTest {
@@ -25,13 +24,15 @@ public static function checkThrowsOnInvalidOffset<T>(
     expect(() ==> $fn('Hello', re"/Hello/", -5))->notToThrow();
     expect(() ==> $fn('Hello', re"/Hello/", 6))->
       toThrow(
-        InvariantViolationException::class,
+        InvariantException::class, // @oss-enable
+        // @oss-disable: InvariantViolationException::class,
         null,
         'Invalid offset should throw an exception',
       );
     expect(() ==> $fn('Hello', re"/Hello/", -6))->
       toThrow(
-        InvariantViolationException::class,
+        InvariantException::class, // @oss-enable
+        // @oss-disable: InvariantViolationException::class,
         null,
         'Invalid offset should throw an exception',
       );
@@ -375,8 +376,10 @@ public function testSplit(
   }
 
   public function testSplitInvalidLimit(): void {
-    expect(() ==> Regex\split('hello world', re"/x/", 1))
-      ->toThrow(InvariantViolationException::class);
+    expect(() ==> Regex\split('hello world', re"/x/", 1))->toThrow(
+      InvariantException::class, // @oss-enable
+      // @oss-disable: InvariantViolationException::class,
+    );
   }
 
   public static function provideToString(